TopWare 18: Liquid/Image.iso/liquid/top1184/gepackt.exe/GRAPHICA.FIL

Text File | 1994-02-22 | 173.7 KB | 4,660 lines

≡about
≡
 ┌──────────────────────────────────────────────────────────────────────┐
 │                            G R A P H I C A                           │
 └──────────────────────────────────────────────────────────────────────┘

 Graphica is a command-driven interactive graphics program for making
 presentation quality graphs on a computer.  This two-dimensional data
 plotting system is designed specifically for scientific and engineering
 applications.  Graphica is easy to use, interactive, powerful and it
 runs on personal computers, mainframes and workstations.  With Graphica,
 you can:

     o   plot data or functions
     o   evaluate and plot mathematical expressions
     o   fit splines, polynomials and smooth data
     o   display and print graphs on hardcopy devices
     o   export graphs in HPGL, PostScript and other output formats
     o   draw text in 11 different fonts, including roman, greek,
         cyrillic and gothic
     o   draw hundreds of specialized symbols
     o   get online help
≡arrow
≡noarrow
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   arrow {tag} {from sx,sy} {to ex,ey} {len} {ang} {type (1-5)}       │
 │   noarrow {tag}                                                      │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The 'arrow' command is used to draw arrows.  All positions (x,y) default
 to 0,0.  The x and y values are real numbers.  These values can be either
 in the paper (inches) or the graph coordinate system (mapped units)
 depending on the status of the location flag (see the LOCATION command).

 The tag is an integer that may be used to identify a given arrow.
 If no tag is given, the lowest unused tag value is assigned
 automatically.  This tag can be used to delete or change a specific
 arrow.  To change any attribute of an existing arrow, use the arrow
 command with the appropriate tag, and specify the parts of the arrow
 to be changed.

 An optional arrow type may be specified.  The default arrow type is
 3 or full.  The available arrow types are:

     type = 1           single wing
     type = 2           single wing with a back line
     type = 3           full
     type = 4           full with a half dimension line
     type = 5           full with a dimension line

 The arrowhead length and width are 20% and 6% of the total arrow length.
 If the arrowhead length is less than 1/8", it will remain at 1/8"
 regardless of the total arrow length.

 Entering 'arrows' by itself simply shows the currently defined arrows.

 Examples:

 to set an arrow pointing from the origin to (1,2) use:
     » arrow to 1.0,2.0

 to set an arrow from (-10,4) to (-5,5), and tag the arrow number 3, use:
     » arrow 3 from -10,4 to -5,5

 to change the preceding arrow begin at 1.1,1.3, use:
     » arrow 3 from 1.1,1.3

 to delete arrow number 2 use:
     » noarrow 2

 to delete all arrows use:
     » noarrow
≡audit
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   audit {'filename'}                                                 │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 This command makes a copy of all your input commands into the given
 filename.  You may later use it as a 'load' or 'input' file.

 Examples:

     » audit 'trace.dat'
     » audit

 in the latter case, a file called 'graphica.odt' will contain a trace
 of anything entered at the command line after entering 'audit'.
≡autoscale
≡noautoscale
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   autoscale {x,y,y2,x2}                                              │
 │   noautoscale                                                        │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 Frequently, it is difficult for the user to select suitable axis limits
 and step sizes, especially if the data being plotted varies greatly from
 one execution of the program to the next.  For this reason Graphica
 provides automatic axis scaling for all axes as the default.

 The autoscale command sets the autoscaling feature for an axis.  If an
 axis is not autoscaled, the default or current map is used when data is
 plotted.

 Entering 'autoscale' by itself simply shows the currently defined scaling.

 Examples:

     » autoscale x
     » noautoscale

 Another example.  Suppose you have a data file with two columns of data,
 x and y but don't know their ranges.  You could do the following:

     » data 'mydata.dat'
     » draw data
     » plot x y

 and determine how the data looks.  The axes are autoscaled.  Then you could
 say,

     » noaxes
     » map x 0 100 y 30 200

 where the mapped range would be your own values and then,

     » draw x y

 would draw the axes with the desired mapped range.
≡noaxes
≡axes
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   noaxes                                                             │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The 'noaxes' command will delete any previously specified axes, so the
 effect is as if the axes had never been drawn.  It is very useful for one
 important reason:  Graphica maintains a list in memory of all the axes that
 have been drawn on the same page.  For example, if you had 2 graphs on one
 page and needed to get a hardcopy, Graphica would have to keep track of
 where everything is so that it could give you an exact reproduction on
 paper of what you had on your screen.  The 'noaxes' command effectively
 wipes out all traces of previously drawn axes and lets you start anew.

 Entering 'axes' by itself simply shows the currently defined axes.

 Examples:

     » noaxes
≡background
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   background {color} {integer}/<name>                                │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 Sets the background color.  See the PEN COLOR command for more
 details about the colors available to use with this command.

 Entering 'background' by itself simply shows the currently defined
 background color.  The default background color is 'black'.

 Examples:

     » background 3
     » back red
≡beep
≡nobeep
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   beep                                                               │
 │   nobeep                                                             │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 These two commands are used to toggle Graphica beeps on and off.
 The default is on.

 Examples:

     » beep

 activates the beep when the screen has been drawn or when there is an error.

     » nobeep

 turns beeping off.
≡character
≡fonts
≡character fonts
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   character {gap,ratio,size,slant} <value>                           │
 │   character {font} <integer>                                         │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 This command sets character attributes such as the font type,
 character gap, ratio, size and slant.

 A font is a collection of characters with a unified design.  The 'font'
 command defines the font style for characters.  Characters may be
 hardware or software generated.  The default font style is 1 which is a
 software generated character.  The software generated character fonts are
 based on a database originally created by Dr. A.V. Hershey while working at
 the U.S. National Bureau of Standards.  They have been reorganized and
 classified into several groups following the ASCII set.  The font sets
 currently implemented are:

     font 1 = simplex roman
     font 2 = simplex greek
     font 3 = complex roman
     font 4 = complex greek
     font 5 = complex cyrillic

 and for registered users ten more:

     font 6 = simplex script
     font 7 = complex script
     font 8 = triplex roman
     font 9 = gothic german
     font 10 = gothic english
     font 11 = gothic italian
     font 12 = symbols I
     font 13 = symbols II
     font 14 = symbols II
     font 15 = symbols IV

 Entering 'character' by itself simply shows the currently defined
 character specs.

 The font files have to be somewhere in your DOS path.  Alternatively,
 you may specify an environment variable called GRAPFONT containing the
 font directory.  For example, if your fonts are in C:\GRAPHICA\FONTS,
 then you would specify,

     SET GRAPFONT=C:\GRAPHICA\FONTS

 somewhere in your autoexec.bat file or in a batch file just before
 running Graphica.  (Font files have the names YY**.BIN where ** is a
 number from 01 to 15.)

 Extended character sets:
 ------------------------

 Fonts 1 and 3 (simplex roman and complex roman) include "extended
 ascii" characters.  This means that you can draw some more characters
 without changing the font.  For example, A with an "umlaut" (two dots)
 is ascii 143, a with a circle on top of it is 134, etc.  The extended
 set is by no means complete yet but I'm getting there.  It maps the
 MSDOS Multilingual (Latin I) code page set from ascii 127 to 212 (so
 far, with a few missing symbols).  To use characters from the extended
 set, lookup TEXT in this help system.

 Examples:

     » character size 0.15 ratio 0.6
     » char gap 0.2 slant -10
     » character font 2
     » font 3

 This last command specifies a font of complex roman style.

 Also see CHARACTER FONT, CHARACTER GAP, CHARACTER RATIO, CHARACTER SIZE,
 CHARACTER SLANT, SUBSCRIPT, SUPERSCRIPT, TEXT and ENVIRONMENT.
≡character gap
≡gap
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   character gap <value>                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The character gap attribute defines the spacing between adjacent
 characters in a text string, in the direction of the character path.
 The character gap is defined as a fraction of the average character box
 size.  The default gap of 0.0 implies that adjacent character boxes are
 to be abutting.  A gap of 1.0 implies that a gap, equivalent to the
 size of the average character box, is to be inserted between adjacent
 characters along the path.  A gap of -0.5 implies that character boxes
 are to partially overlap.

 Example:

     » character gap 1.0
≡character ratio
≡ratio
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   character ratio <value>                                            │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 Specifies the ratio of the width of the character to its height.  The
 default character ratio is 1.0.

 Example:

     » character ratio 0.8
≡character size
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   character size <value>                                             │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The character size attribute defines the vertical size of the
 characters in default units (in, cm, mm).  Graphica sets the default
 character size of all strings and labels to 0.17 in.

 Example:

     » character size 0.2
≡character slant
≡slant
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   character slant <value>                                            │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 Specifies the number of degrees the characters tilt from the vertical.
 The sign convention for the direction of rotation is as follows:

     + clockwise
     - counterclockwise

 The default character slant is 0.0 degrees.

 Example:

     » character slant 25
≡cd
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   cd <directory-name>                                                │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The 'cd' command changes the working directory to <directory-name>.

 Examples:

     » cd c:\work
     » cd ..
     » cd c:\work\examples
≡circle
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   circle {center at <x>,<y>} {radius <value>}                        │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 This command draws a circle with the given radius in user default
 units at the given position (also in user default units).

 Entering 'circles' by itself simply shows the currently defined circles.

 Example:

     » circle radius 2.0 center at 3.0 4.0.
≡clc
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   clc                                                                │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The 'clc' command erases the current text screen.

 Example:

     » clc

 See also CLEAR.
≡clear
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   clear                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The 'clear' command erases the current graphics screen or output device
 as specified by output.  It also resets all internal flags to the default
 state found when entering Graphica, i.e. no axes, no frame, default map,
 etc.  This usually generates a formfeed on hardcopy devices.

 Example:

     » clear

 See also CLC and DEFAULT.
≡column
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   column <integer> {is} {x,y,y2,x2}                                  │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 This powerful command allows the assignment of any data column read
 from a user file to a certain axis.

 Entering 'columns' by itself simply shows the currently defined columns.

 Examples:

      » column 3 y2
      » column 2 is x 1 is y

 assigns column 3 of a data file to the x-axis and column 1 to the y-axis.
 Then plot x y add points will generate a graph of column 3 versus column 1.

 Also see PLOT.
≡comment
 ┌──────────────────────────────────────────────────────────────────────┐
 │   comments                                                           │
 └──────────────────────────────────────────────────────────────────────┘

 Comments are supported as follows:  a '#' (hatch) may appear in most
 places in a line and Graphica will ignore the rest of the line.  It
 will not have this effect inside quotes or inside numbers (including
 complex numbers).

 Examples:

     » # test file
     » echo           # echo all commands from here on out
     » # map axes
     » map x 0 10 y 0 10
≡contributions
 ┌──────────────────────────────────────────────────────────────────────┐
 │ GRAPHICA Copyright (c) 1992-93 Antonio Montes.  All rights reserved. │
 └──────────────────────────────────────────────────────────────────────┘

 GRAPHICA is shareware and as such is NOT FREE for use in a business,
 commercial, government, or institutional environment.  Registration of
 GRAPHICA for personal (not at the office) use is optional.  If you like
 this program and find it useful, you can support its continued development
 by sending me a contribution of NFL 50.- (dutch guilders) or US$25.00
 (US dollars).  Your financial support is needed to encourage further
 improvements to GRAPHICA.  Business, commercial, government, or
 institutional GRAPHICA users must register GRAPHICA after a 30-day
 evaluation period.  If you want to see additional features in GRAPHICA,
 please send in a contribution.  Feel free to contact me for any reason.

 ┌──────────────────────────────────────────────────────────────────────┐
 │   Antonio Montes      Internet address : [e-mail]  │
 │   Postbus 13          CompuServe userid: 71031,1162                  │
 │   2350 AA Leiderdorp                                                 │
 │   The Netherlands                                                    │
 └──────────────────────────────────────────────────────────────────────┘
≡data
≡file
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   data {from} {file} {'filename'} {autox}                            │
 │            x(1) y(1)                                                 │
 │            x(2) y(2)                                                 │
 │            x(3) y(3)                                                 │
 │              .    .                                                  │
 │            x(n) y(n)                                                 │
 │   end                                                                │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 Discrete data contained in a file can displayed by specifying the name
 of a data file (enclosed in quotes) on the plot command line.  Using the
 'data' command simply reads in the data from a file, without plotting it.

 If the data to be plotted is on a data file already, then the command
 'data {from} {file}' opens the data file and reads data points.

 Data files may contain one or more data points per line.  If more than
 one data point is encountered on a line, the data points in a given
 column are referred to as columns.  If just one value is given on a
 line, the program will use the number of the coordinate as the x value.
 Coordinate numbers start at 1 and are incremented for each data point
 read.

 Lines beginning with # will be treated as comments and ignored.
 Graphica will also ignore anything within two double quotes before
 data on a line.

 Numbers can be separated by a comma or one or more blanks (free format).
 There is no limit to the number of data points possible (well, until
 memory is exhausted.)  Optionally, data pairs read interactively can be
 put on a single input line.  You can't input multiple columns of data
 interactively, just two columns.

 In data files, up to 20 columns of data can be read in on a line.  These
 data can in turn be assigned to different axes with the COLUMN command
 later on.

 Specifying 'autox' will result in the automatic assignment of the x
 values starting from 1.  In other words, you may read in one or more
 columns of y data only and Graphica will assign the x values for you.

 It is possible to have several sets of data one after another in the
 same data file.  Simply separate the sets with blank lines:  Graphica
 will read each set in sequence and plot the curves one after another.
 This way you won't need a bunch of data filenames in one script file:
 just put all the data in one data file separated by blank lines.

 Also see COLUMN.

 Examples:

 Interactive data input:

     » data                   # interactive data input only
     » 1.0,10.0 2.0,20.0 3.0,30.0 4.0,40.0 5.0,50.0
     » end

 Data file input:

     » data 'gel3.dat'
     » data file 'comfil'
     » data 'test.dat' autox

 In this last example, if 'test.dat' contained only one column of data
 (the y values), x would be assigned automatically by Graphica.
≡default
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   default <parameter>                                                │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The 'default' command resets parameter settings to their default value.
 The available parameters are:

     all
     character
     division
     map
     tic
     unit

 Examples:

     » default all

 resets all the above parameters to their default value.  Graphica does
 the equivalent of 'default all' at startup or when a 'paper size'
 command is given.

     » def map

 resets all axes mapping to the default state.

 Also see CLEAR.
≡del
≡delete
≡rm
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   del <file>                                                         │
 │   rm <file>                                                          │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The 'del' command deletes a file.  Pathnames, wildcards, and drive
 designators may be used in the usual way for your operating system.
 Other operating system commands can be issued using the $ character
 followed by a command.  'rm' is the equivalent UNIX command.

 Examples:

     » del script.plt

 deletes the ASCII file script.plt.

     » del foo

 deletes the ASCII file foo.

 Also see DIR, SHELL, TYPE and WHAT.
≡digitize
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   digitize                                                           │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 Establish the (x,y) coordinates of a point on the plot.  This position is
 relative to the graphic origin (0,0), the lower left hand corner of the
 paper on which the plot appears, and is given is the default unit system.

 If the mouse driver is loaded and your graphics card supports it (I
 can only make it work with VGA), a crosshair will appear and you may
 move it around by moving your mouse.  By pressing any mouse button the
 point will be digitized.  If the mouse can't be used, the keyboard
 (up/down/left/right) arrow keys will let you move a cross-hair around
 until you hit the enter (or return) key.  Pressing H or D will half or
 double the cursor step size.

 Example:

     » digitize

 will give you the coordinates of the point on which the cursor was on the
 plot before you pressed return, in inches, cm or mm.
≡dir
≡ls
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   dir <file>                                                         │
 │   ls <file>                                                          │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The 'dir' command lists the files and subdirectories in a directory.
 Pathnames, wildcards, and drive designators may be used in the usual way
 for your operating system.  Other operating system commands can be issued
 using the $ character on the very first position of a line followed by a
 command.  'ls' is the equivalent UNIX command.

 Examples:

     » dir

 lists all files in the current directory.

     » dir *.plt

 lists all files with an extension of .plt in the current directory.

 Also see DEL, SHELL, TYPE and WHAT.
≡divisions
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   divisions {x,y,y2,x2} <major> <minor>                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 Graphica draws a tic at each axis value (major tic) and other tic marks
 in between (minor tics).

 The 'divisions' command determines the number of major and minor tic
 marks.  These two numbers must be integers.  Major and minor tic marks
 are one less than the total number of divisions for a particular axis.
 For example, if the x-axis range is 0 to 25, a good selection for major
 divisions would be 5.  The major tic marks will appear at 5, 10, 15,
 and 20.  5 could be chosen as the number of minor divisions.  This
 results in four minor tic marks between two major ones.  The default
 divisions are 5 and 2.

 Entering 'divisions' by itself simply shows the currently defined divisions.

 Example:

     » divisions x 6,3 y 4,2
≡draw
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   draw {x,y,y2,x2} {mask} {reflect}                                  │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 Draws the specified axis with the given range, tic size and number of
 divisions.  The key words 'x,x2,y,y2' may be followed by two optional
 key words, 'mask' and/or 'reflect'.  If 'mask' is specified, that axis
 is drawn with the major and minor tic marks but with no numbers or
 label.  If the 'reflect' option is used, a mirror image of that axis is
 drawn.

 Example:

     » draw x reflect y reflect.

 draws the x and y axes with opposite mirror images.

 Note:  You may draw more than one axis of the same kind by suitably changing
 the subplot area.
≡dummy
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   dummy <dummy-var-1> <dummy-var-2>                                  │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 By default, Graphica assumes that the independent variable for the
 'plot' command line is 'x'.  These variables are called the dummy variable
 because it is just a notation to indicate the independent variable.  The
 'dummy' command changes the default dummy variable names.  For example,
 you may find it more convenient to call the dummy variable 't' when
 plotting time functions.

 Entering 'dummy' by itself simply shows the currently defined dummy
 variables.

 Examples:

     » dummy t
     » dummy u,v

 See also FUNCTIONS and WHO.
≡dump
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   dump {device-type} {'filename'}                                    │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 Generates hardcopy output into a file.  The available device types are:

          dj, epson, epsf, hpgl, hpgl2, lj2, lj4, pic, postscript

 If the filename is omitted, Graphica will use a default filename of the
 form 'graphica.xxx' where xxx is one of:

          dj5, prn, eps, hpg, lj2, lj4, pic, ps

 depending on the chosen device type.  If the device type is missing and
 you have defined the environment variable GRAPDUMP, then this device will
 be used.  A device type specified on the command line overrides any device
 type previously specified in GRAPDUMP.  You will get an error message if
 Graphica can't find a device type somewhere (either in the environment or
 on the command line.)

 If you wish to dump directly to a device, there are two options.  First,
 you can dump to a file and then use the OS command $ to perform a copy
 to a printer or plotter.  The second option is not to use the dump command,
 but to use the OUTPUT command and then do a SHOW.  Both achieve the same
 purpose.  Let's illustrate both on the DOS version:

     » dump postscript
     » $copy graphica.ps prn

 or

     » (do some graphics on screen)
     » output prn
     » term postscript
     » show

 This last example would 'redraw' everything in PostScript to the printer
 specified by prn.

 Examples:

     » dump hpgl 'plotter.dat'

 generates a file called plotter.dat containing HPGL commands.  You may
 send this file directly to an HP plotter or import it into another
 program which accepts HPGL commands, such as WordPerfect, Ventura
 Publisher, etc.

     » dump hpgl

 does the same thing except it dumps the output to 'graphica.hpg'.

     » dump 'plotter.dat' hpgl

 same effect as the first example.

     » dump

 In this case, if GRAPDUMP=post, a postscript file will be generated,
 but you will get an error message otherwise.

     » dump post "graph.ps" color

 generates a PostScript file called 'graph.ps' for color printers.

 On DOS systems,

     » dump epson

 generates a binary file called 'graphica.prn' which you may send to an
 Epson-compatible printer (after you're out of Graphica or by 'shelling'
 out to DOS) by typing:

     C:\>copy/b graphica.prn lpt1:

 The resolution of this plot is 512 x 384 pixels on a 9-pin dot-matrix
 printer.

 Also see ENVIRONMENT, HPGL, LASERJET, OUTPUT, TERMINAL and POSTSCRIPT.
≡echo
≡noecho
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   echo                                                               │
 │   noecho                                                             │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The 'echo' command causes all input typed at the terminal or picked up
 from a load file to be displayed at the terminal.  This is useful with
 a load file because progress can be monitored.  The default is 'noecho.'

 Examples:

     » echo

 switches echoing on

     » noecho

 switches echoing off.
≡quit
≡exit
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   exit                                                               │
 │   quit                                                               │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The commands 'exit' and 'quit' will terminate Graphica.  These commands
 will clear the output device (as the clear command does) before exiting.
 If this command is used in a script file, program execution halts
 immediately.  Do not use this command until you really want to exit the
 program.

 Example:

     » exit

 and you will be back at the command line prompt.
≡exponent
≡noexponent
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   exponent                                                           │
 │   noexponent                                                         │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 Use this option to select either a fixed or exponential format for
 logarithmic axis tic mark labels.

 Exponential format is displayed as the number 10 with an exponent.  For
 example, the value 0.001 will be displayed as 10 to the power -3 on a log
 axis with exponential format.

 Example:

     » exponent

 Also see FORMAT.
≡format
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   format {x,y,y2,x2} <integer>                                       │
 │   format {x,y,y2,x2} ({"<lab>"} <pos> {, {"<lab>"} <pos>}...)        │
 │   format {log} n                                                     │
 │   format {long} {short}                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The main 'format' command controls the format of numbers plotted next
 to the major tic marks.  The parameter in angle brackets indicates the
 number of digits drawn after the decimal point.  A -1 or 0 causes the
 numbers to be displayed in integer format.  The default value for the
 number of digits to the right of the decimal point is 1.

 The ("<label>" <pos>, ...) format allows non-numeric tic labels.  Each
 set of tics can have an optional label.  The label is a string enclosed
 by quotes, such as "hello".  The label may even be empty.  You have to
 include the ( and ) for the non-numeric tic labels to work.  Of course,
 the corresponding axis will have to be mapped properly for user-defined
 labels to work.  That is, if you map the y axis from -10 to -5 and
 specify "format y ("one" 1, "two" 2), you'll get labels like "-10",
 etc. instead of "one", "two", etc.

 For logarithmic axes, 'format log' controls how often major and minor
 tic marks should be labeled.  Enter a frequency of:

    n = 1     to label all minor tics and all major tics
    n = 2     to label even minor tics and all major tics
    n = 3     to label minor tics 2 and 5, and all major tics
    n = 4     to label minor tic 3, and all major tics
    n = 5     to label only major tics.

 The result of any Graphica assignment statement is displayed on the
 screen.  The numeric display format can be controlled using the
 'format' command.  The default format, called the 'short' format, shows
 approximately 5 significant decimal digits.  For the 'long' format
 (approx.  15 digits) the last significant digit may appear to be
 incorrect but the output is actually an accurate representation of the
 binary number stored in the computer.

 Entering 'format' by itself simply shows the currently defined formats.

 Examples:

     » format x 2 y 3

 In this example, the x-axis labels will be printed with 2 decimal
 points and the y-axis labels with 3.

     » format x ("Jan" 1, "Feb" 2, "Mar" 3)
     » format y ("bottom" 0, "" 10, "top" 20)

 Here, we're using the user-defined axis labels.  "Jan" will be printed
 instead of a "1", "Feb" instead of 2, and "Mar" instead of 3.  In the
 second example, the label "bottom" will appear at the "0" position, and
 "top" will appear at the "20" position.

     » format log 2

 in this case, the even minor tic marks will be labeled (2,4,6,8) for
 each log cycle.

     » a = 4./3.
     » format short
     » print a

     a = 1.33333

     » format long
     » print a

     a = 1.333333333333333

 Also see EXPONENT.
≡frame
≡noframe
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   frame                                                              │
 │   noframe                                                            │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 This command draws a frame around the subplot area.  'noframe' cancels
 this effect.

 Example:

     » frame

 produces a frame around the subplot area.
≡grid
≡nogrid
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   grid {pen {style} <integer>} {color <integer>/name}                │
 │   nogrid                                                             │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 You may specify whether or not to put a set of horizontal and vertical
 reference lines on a plot at the same points as the axis tic marks.
 The grid may make it easier to read values off and may improve plot
 appearance.

 The 'grid' command sets an internal flag that signals the axis drawing
 routine to generate a grid.  'nogrid' cancels this effect for subsequent
 axis draws.  The 'pen' and 'color' keywords may be specified to change
 the appearance of the grid.  The defaults are:

     nogrid, pen = current pen style + 2, color = red.

 Examples:

     » grid
     » draw x

     » grid pen 2 color 3

     » grid color cyan
≡help
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   help <topic>                                                       │
 └──────────────────────────────────────────────────────────────────────┘

     Invoking the HELP utility
     -------------------------
 The HELP utility displays information about requested Graphica topics.
 From the Graphica command level (in response to the > prompt), you can
 display a list of topics for which help information is available by
 typing HELP (or ?) and pressing the RETURN key.  The system responds by
 displaying a brief description of Graphica, followed by a list of
 topics for which help is available, followed by the prompt "topic?".

     Specifying topic names
     ----------------------
 To display information on a particular topic, respond to the prompt by
 typing the name of the topic and pressing the RETURN key.

     Subtopic information
     --------------------
 The information displayed by HELP on a particular topic includes a
 description of the topic and a list of subtopics that further describe
 the topic.  To display subtopic information, type one of the subtopic
 names from the list in response to the "subtopic?" prompt.

     Special responses to prompts
     ----------------------------
 If you press RETURN in response to the "subtopic?" prompt instead of
 typing a subtopic name, the "topic?" prompt reappears,  enabling you to
 enter another topic name.  If you press RETURN in response to the
 "topic?" prompt, you will exit from HELP.  You can also exit HELP by
 pressing 'q' or ESC (escape key) at the "press any key to continue"
 prompt.

 You can type a question mark (?) in response to any of the prompts to
 redisplay the most recently requested text and a list of topic or
 subtopic names.  For example, if you type ? in response to the
 "subtopic?" prompt, a list of subtopics is displayed followed by the
 "subtopic?" prompt.

 Examples:

     » help subplot
     » help ?
     » help

 Also see ENVIRONMENT and STARTUP.
≡hpgl
≡hpgl2
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   terminal {hpgl,hpgl2}                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The hpgl device driver can also output HPGL-2 commands.  This is
 especially useful when you'd like filled symbols on the plotter.
 I haven't implemented filled symbols in software yet.  Any HPGL-2
 commands sent to an hpgl plotter like the HP7475 (or a program
 that understands hpgl) will be ignored.

 Examples:

     » term hpgl
     » dump hpgl "graph1.hpg"
     » dump hpgl2 "graph2.hpg"

 Also see DUMP, OUTPUT and TERMINAL.
≡labels
≡titles
≡nolabels
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   label {top,bottom,right,left} "label text"                         │
 │   label {tag} "label_text" {at <x>,<y>} {justification} {<angle>}    │
 │   label {origin} <integer>                                           │
 │   title "title text"                                                 │
 │   nolabel {tag}                                                      │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 By default, the text is placed flush left against point (x,y).  If you
 want to adjust the way the label is positioned with respect to the
 point (x,y), add the parameter <justification>, which may be 'start',
 'stop' or 'center'.  This indicates that the point is to be at the
 left, right or center of the text.  The <justification> may be
 abbreviated.

 The top label lies above the plot frame line.  The bottom label is
 drawn below the frame.  'start', 'center' and 'stop' cause the
 program to halt for pen positioning if a label position was not
 specified.  The start label is drawn left-justified.  The center
 label is centered around (x,y) and the stop label is right-justified.
 the top and bottom labels are centered and each subsequent label goes
 either above or below the previously drawn label.  The label will be
 drawn at an 'angle'from the horizontal.

 'tag' is an integer that is used to identify the label.  If no tag
 is given, the lowest unused tag value is assigned automatically.  The
 tag can be used to delete or change a specific label.  To change any
 attribute of an existing label, use the label command with the
 appropriate tag, and specify the parts of the label to be changed.

 The 'xlabel' command is equivalent to the label bottom command (and so
 are the 'x2label', 'ylabel' and 'y2label' commands equivalent to the
 label top, left and right commands.)

 Entering just 'labels' or 'titles' simply shows the currently defined
 labels and titles.

 Examples:

 to set a label at (1,2) to "y=x" use:
     » label "y=x" at 1,2

 to set a label "y=x^2" with the right of the text at (2,3), and
 tag the label number 3, use:
     » label 3 "y=x≡U2" at 2,3 stop

 to change the preceding label to center justification, use:
     » label 3 center

 to delete label number 2 use:
     » nolabel 2

 to delete all labels use:
     » nolabel
≡laserjet
≡deskjet
≡dj
≡lj2
≡lj4
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   terminal {dj,lj2,lj4} {low,med,high} {us,a4}                       │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The LaserJet II and deskjet 500 drivers can output graphs in three
 different resolutions: low (75 dpi), medium (150 dpi) and high (300
 dpi).  The LaserJet 4 can also print graphs in three resolutions:
 low (150), medium (300) and high (600 dpi).

 Graphica chooses the highest resolution possible according to how
 much memory is present.  Currently, the Borland-compiled version of
 Graphica can generate 150 dpi (dots per inch).  The Watcom-compiled
 version will produce the highest resolution since it works in
 protected mode.

 The 'us' and 'a4' switches are used by the driver to select the
 correct paper tray size installed in the printer.  The default is
 'a4' for a paper size of 210 mm by 297 mm.  The 'us' paper tray has
 dimensions of 8.5 by 11 in.

 Examples:

     » term lj2 med
     » dump lj2 "graph1.lj2" med
     » dump lj4 high us
     » dump dj "graph2.dj5"

 Also see DUMP, OUTPUT and TERMINAL.
≡legends
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   legend {framed} {offset <value>} {left} {center}                   │
 │          {right} {flat} {stacked} {at <x>,<y>}                       │
 │          "legend string"                                             │
 │          {pen {style} {width} <integer>}                             │
 │          {length {value}}                                            │
 │          {symbol {<integer>}/{name}}                                 │
 │          {{pen} color {<integer>}/{name}}                            │
 │   end                                                                │
 └──────────────────────────────────────────────────────────────────────┘
 Description:

 This command places a legend at a digitized location.  This location
 is (x,y) default units away from the lower left hand corner of the
 current page size.  If a line pattern is specified a small segment of
 the line is drawn before the text.  If a symbol is specified, that
 symbol is drawn before the text.  'pen', 'length', 'symbol' and 'color'
 can be specified in any order.

 The 'color' command applies to the entire group (line segment, symbol
 and text) but the 'pen style' and 'pen width' commands apply only to
 the line segement and the symbol, not the text.  The text style and
 width will be those in effect just before the legend was specified.  If
 you want a legend with thick letters, specify 'pen width 3' before the
 'legend' command.

 The 'legend' command processes information until the word 'end' is
 encountered.  'left', 'center' and 'right' are keywords to place the
 whole legend (lines, symbols and text) at that relative given position.

 'offset' specifies the separation between lines in a given legend in
 multiples of the current character size.  The default is 2.5 times the
 character size.

 'length' specifies the length of the line drawn, if one has been asked
 for with the 'pen' keyword.  It is in default paper units (inches).

 'framed' places a frame around the legend.  This frame is also a
 masked area.  So if you draw a legend first, then anything drawn "over"
 the legend will effectively be masked out.  You can only have one
 "masked" area (see MASK).

 'flat' is a keyword used to draw all the legend information in one
 line (Lotus-style).  The default mode of operation is 'stacked'.

 Entering 'legends' by itself simply shows the currently defined legends.

 Examples:

     » legend framed at 2.0 3.0
     » 'This is one line with a symbol' symbol square
     » color 3 'This second line is in another color'
     » pen 4 length 1.0 'one inch line'
     » end

     » legend center at 5.0,4.0
     » symb 1 'experimental data set 1'
     » symb 2 'experimental data set 2'
     » pen 3 'simulation results'
     » end

     » legend center at 5.0,4.0 flat framed
     » pen 1 'data 1'
     » pen 2 'data 2'
     » end

 This last example draws all the legend information on one line as
 compared to the other two examples above which draw stacked legends.

 Also see the example script files 'legend.plt' and 'flat.plt' for
 more examples.
≡lines
≡nolines
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   line {<tag>} {from <sx>,<sy>} {to <ex>,<ey>}                       │
 │   noline {<tag>}                                                     │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 This command is used to make more complicated diagrams by specifying
 each line to be drawn.  The linked list so created may be corrected and
 modified by specifying new coordinates.  'noline tag' eliminates the
 line from the list.  The coordinates can also be mapped units.  Just
 precede the 'line' command by a 'location mapped' command.

 Entering 'lines' by itself simply shows the currently defined lines.

 Examples:

     » line from 3,4 to 6,8
     » line 2 to 3,5

 this last command modifies line number 2 to end at (3,5).

 See also LINETO and MOVETO.
≡lineto
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   lineto <ex>,<ey>                                                   │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 This command draws a line from the current cursor location to the
 specified location.  The coordinates can also be mapped units.  Just
 precede the 'lineto' command by a 'location mapped' command.

 Entering 'lineto' by itself simply shows the currently defined lines.

 Example:

     » moveto 3,4
     » lineto 6,8.5

 moves the cursor to a point (3,4) inches away from the origin and
 draws a line to point (6,8.5).

 See also LINE and MOVETO.
≡load
≡batch
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   load <filename>                                                    │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The 'load' command executes each command line of the specified input
 file as if they had been typed in interactively.  Files created by
 the 'audit' command can later be loaded.  Any text file containing
 valid commands can be created and then executed by the 'load'
 command.  Files being loaded may themselves contain 'load' commands.
 The 'load' command must be the last command on the line.  The name of
 the input file must be enclosed in single or double quotes if there
 are any non-character elements in the name, e.g.  file.dat has a dot
 in it so you must enclose it in quotes.

 You may also enter a script file directly at the command line prompt.
 In general, if you input the name of something to GRAPHICA, for example
 'whoa', the GRAPHICA interpreter goes through the following steps:

     1) looks to see if 'whoa' is a variable
     2) checks to see if 'whoa' is a function or variable definition
     3) checks if 'whoa' is a built-in command
     4) checks to see if 'whoa' is an expression
     5) looks in the current directory (or search path on DOS systems)
        for a script file named 'whoa.plt'

 Note: If you have a script file called 'spline.plt' and simply enter
 'spline' at the command line, you'll be executing the spline command
 rather than calling in the 'spline.plt' script file.

 Examples:

     » load 'work.plt'
     » load "function.plt"
     » my.plt
     » myplot

 The 'load' command is performed implicitly on any file names given as
 arguments to Graphica.  These are loaded in the order specified, and
 then Graphica switches to interactive mode.  For example,

     C:\GRAPH\graphica myown.plt

 will load Graphica, execute the script file myown.plt and, after a key
 is pressed, switch to the > command line.  To simply exit to the OS,
 enter q or Q.  Notice how quotes are not needed to specify data files
 at the OS command line level.  You may specify more than one file as
 arguments to Graphica,

     C:\GRAPH\graphica first.plt second.plt
≡location
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   location {default,mapped}                                          │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 This command allows giving mapped (x,y) positions in commands like
 'arrow', 'circle', 'label', 'legend', 'line', and 'rectangle'.

 Examples:

     » location mapped

 turns a flag on so that the (x,y) location is interpreted as being in
 mapped units.

     » location default

 turns the flag off so that the (x,y) location is interpreted as being
 in user default units (inches, for example, which is the default.)

 'location' by itself gives the status of this flag.
≡map
≡nomap
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   map {x,y,y2,x2,t} <min> <max>                                      │
 │   nomap                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The command 'map' defines the ranges of the data for the generation
 of axes.  These values determine the numbers that appear along the
 axes.  The x range specifies a range for the bottom x-axis, the x2
 range for the top x-axis, the y range is for the left y-axis and the
 y2 range for the right y-axis.  If this command is not specified the
 subplot area is mapped automatically from the minimum and maximum
 (x,y) data values entered with the data command.  (This latter
 procedure will only map the (x,y) axes, not the (x2,y2) axes.)  The
 mapping of 't' is used in polar plots only.

 Mapping can be turned off with the command 'nomap'.

 Entering 'map' by itself simply shows the currently mapped axes.

 Examples:

     » map x 0,10 y 0.0,100.0
     » map y2 25,-10 x 100,200
     » map t 0 3*pi

 See also PARAMETRIC, POLAR, and PLOT.
≡mask
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   mask {area} {on} {off} {<x1>,<y1>,<x2>,<y2>}                       │
 │   nomask                                                             │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The 'mask' command defines a masking area.  Nothing is drawn over the
 masked area if it is currently active.  The 'legend' command for
 example, creates a mask over the specified legend block and no points
 or lines are drawn over it.  Use 'nomask' to turn masking off or 'mask
 on'/'mask off' to toggle the mask status.

 Entering 'mask' by itself simply shows the currently defined mask.

 Examples:

     » mask 2,3 5,8
     » nomask
     » mask on
     » mask off
≡memory
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   memory                                                             │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The 'memory' command gives the number of bytes left in system RAM in
 the DOS version of Graphica compiled with Borland C++.  Other versions
 of Graphica compiled in 32-bit environments (Coherent, WATCOM C, etc.)
 do not implement this command for obvious reasons (it's not needed).

 Example:

     » mem

 would give you the following message:

     System RAM available:   378,588 bytes.
≡moveto
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   moveto <sx>,<sy>                                                   │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 This command moves the graphics cursor to the specified location.
 The coordinates can also be mapped units.  Just precede the 'moveto'
 command by a 'location mapped' command.

 Entering 'moveto' by itself simply shows the currently defined lines.

 Example:

     » moveto 3.3,4
     » lineto 6.2,8

 moves the cursor to a point (3.3,4) inches away from the origin and
 draws a line to point (6.2,8).

 See also LINE and LINETO.
≡origin
≡noorigin
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   origin {x,y} {axis} <other coordinate value>                       │
 │   noorigin                                                           │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The normal plot style is to have the data plotted in a box.  It is
 possible to cause either the x or y-axis, or both, to be drawn in such
 a way that they cross at an arbitrary value.  Unless told otherwise,
 Graphica will always draw the axes with their origin values at the
 physical origin (left bottom side of the graph).

 The origin command specifies the axis origin in user defined coordinates.

 Entering 'origin' by itself simply shows the currently defined axis origins.

 Examples:

     » origin x 0 y 0
     » origin x axis 0
     » norigin
≡output
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   output {<filename>} {stdout} {com} {prn}                           │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 By default, plots are displayed to the standard output (stdout).  The
 'output' command redirects the display to the specified file or device.
 The filename must be enclosed in quotes.  If the filename is omitted,
 output will be sent to the standard output.

 If you're sending output to the communications port (DOS version), make
 sure you have configured your serial port with the 'mode' command.  For
 example,

     mode com1:96,n,8,1,p

 configures a serial port for use at 9600-baud, with no parity checking,
 8 bits per character, one stop bit, and with retries.  Graphica can
 only use the 'com1:' port for output when using 'output com'.

 Example:

     » output 'output.dat'

 sends output to the file 'output.dat'

     » output com

 sends output to comm port 1 (com1:)

     » output prn

 sends output to the printer port (prn).

 Also see DUMP, OUTPUT and TERMINAL.
≡paper
≡border
≡noborder
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   paper {size} <dx> {by} <dy> {default}                              │
 │   border                                                             │
 │   noborder                                                           │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The most basic elements of a plot are the paper (or page) and the
 subplot area.  The paper size usually coincides with the graphics device
 hardclip limits, that is, no plotting can be done outside this region.

 The paper command defines the size of the paper.  Graphica sets the
 page limits to the standard 11.0 by 8.5 inch paper size.  If a raster
 graphics terminal is being used the page border is also drawn so that the
 relative size of the plot can be ascertained.  This page border may be
 turned off by using the command 'noborder' and on also by using 'border'.

 When paper default is specified, the paper size will be reset to its
 default value.  The 'paper size ' command is also used to indicate that
 a new plot is going to be generated.

 Entering 'paper' by itself simply shows the current paper dimensions.

 Examples:

     » paper default
     » paper 8.5 by 11
     » pap size 11 8.5

 Any of these three resets the paper size to the standard size of 11 by 8.5
 inches.

     » border
     » noborder

 These two commands turn the paper size outline drawing on and off,
 respectively.
≡parametric
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   parametric {plot} t tmin,tmax fx(t),fy(t)                          │
 │              {connect {points}} {add {symbols}}                      │
 │   where                                                              │
 │     t     = any dummy variable                                       │
 │     tmin  = minimum value of the dummy variable                      │
 │     tmax  = maximum value of the dummy variable                      │
 │     fx(t) = x coordinate of each point in the curve                  │
 │     fy(t) = y coordinate of each point in the curve                  │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The plot command allows plotting curves in Graphica in which you give
 the y coordinate of each point as a function of the x coordinate.  You
 can also use Graphica to make parametric plots.  In a parametric plot,
 you give both the x and y coordinates of each point as a function of a
 third parameter, say t.  It takes two parametric function
 specifications in terms of the parametric dummy argument to describe a
 single graph.  The order the parametric functions is xfunction,
 yfunction.  Each function operates over the common parametric domain.

 Examples:

     » parametric plot t 0,2*pi sin(t) sin(2*t)
     » parametric t 0,2*pi sin(t) cos(t)
     » parametric plot x 1,4 log(x) log(x**2+x**6)

     » r(t) = (3*cos(t)**2-1)/2
     » parametric plot t 0 2*pi r(t)*cos(t) r(t)*sin(t)

 See also FUNCTIONS, PLOT and POLAR.
≡pause
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   pause {<expression>} {"string"}                                    │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 Halts execution until a user responds at the keyboard.  'pause' is
 useful in conjunction with 'load' files.  It displays any text
 associated with the command and then waits the specified amount of
 time.  This allows one to build a load file and control the amount of
 time a finished graph is displayed.  The first argument can be a
 negative or a positive integer.  Choosing -1 will have Graphica wait
 until any key is hit.  A positive integer will have Graphica wait for
 the specified number of seconds.

 The expression and string are optional.  If a string is present it
 must be enclosed in quotes.  If no expression is given, 'pause' waits a
 default time of 3 seconds.

 Examples:

     » pause     # Wait a default three seconds
     » pause 3   # Wait three seconds
     » pause 10  "Isn't this great?  It's a cubic spline."
     » pause -1  # Wait until a carriage return is hit
     » pause -1  "Hit return to continue"
≡pen
≡color
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   pen {style} {speed} {width} <value>                                │
 │   pen {color} <integer>/{name}                                       │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 With the 'pen' command, several parameters may be specified, as follows:

 To distinguish between the lines of a multiline plot, 'style' defines
 the type of the line pattern to use when connecting data points or
 drawing lines.  The default is 1 (a solid line).  All drawing commands
 are affected by the 'pen style' command.  In other words, the line type
 remains in effect until changed.  Issue a new 'pen style' command
 whenever you wish to respecify the line pattern.  There are 8 (eight)
 pen styles available.

 'width' defines the pen width in pixels or points.  This feature is
 only available in devices with variable pen thickness capability.  There
 are 8 (eight) pen widths available, with 1 being a line 1 pixel thick.
 This is the default.

 'speed' defines the pen speed in a pen plotter in cm/sec.  The speed
 defaults to the output device's default.  (On an HP7475 plotter, this is
 30 cm/sec.)

 'color' defines the pen color by color code or by color name.  Colors are
 assigned to numbers that in turn correspond to the pen numbers on a
 hardware device (display screen, plotter, printer, etc.).  There are
 currently 16 colors defined:

          0 - black                    8 - lgray
          1 - blue                     9 - lblue
          2 - green                   10 - lgreen
          3 - cyan                    11 - lcyan
          4 - red                     12 - lred
          5 - magenta                 13 - lmagenta
          6 - brown                   14 - yellow
          7 - gray                    15 - white

 Entering 'color' by itself simply shows the current drawing specifications.
 The default color upon Graphica startup is green (2).

 Examples:

     » pen style 1, color 3
     » pen width 3
     » pen speed 15 (cm/s)

 Also see DUMP, POSTSCRIPT and TERMINAL.
≡plot
≡noplot
≡nodata
≡errorbars
≡connect
≡add
≡needle
≡step
≡autox
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   plot 'data-file' {autox}                                           │
 │        {connect {points}} {add {symbols}}                            │
 │        {needle} {step} {errorbars {itype}}                           │
 │   plot {data} {x,y,x2,y2}                                            │
 │        {connect {points}} {add {symbols}}                            │
 │        {needle} {step} {errorbars {itype}}                           │
 │   plot 'definition' <function>                                       │
 │        {connect {points}} {add {symbols}}                            │
 │   plot {p pmin pmax} <function>                                      │
 │        {connect {points}} {add {symbols}}                            │
 │   (no)plots                                                          │
 └──────────────────────────────────────────────────────────────────────┘

 Definition:

 This command allows you to plot data, functions and data files.  It is
 the primary Graphica command.

 'data-file' the name of a data file enclosed in quotes.  The filename
 may be followed by the 'autox' keyword as in the data command.  In that
 case, the x values are assigned automatically starting from data point
 number 1.

 If 'data' is specified, previously read-in data is plotted. 'autox'
 may also be specified.

 <function> is a mathematical expression and may optionally be preceded
 by a range specification.

 'connect' causes the points to be connected by a straight line of
 the specified default line pattern.

 For plots with more than one line of data, it may be difficult to tell
 the difference between the lines.  For this reason, Graphica includes
 the capability of marking each point in a line with a symbol.  'add'
 causes the specified symbol to be displayed at each data point.
 Leaving out the word 'add' just draws a line through the data points.

 'needle' makes the plot come out such that the y data values are
 plotted as needles perpendicular to the x axis.

 'step' makes a step plot, useful, for example, for plotting production
 data versus years.

 The 'errorbars' keyword lets you add error bars to the plotted data
 points.  An optional integer specifies the type, 1 = no tics, 2 =
 tics at end of bar.  Error bar values are read in one of two ways:
 (1) from columns 3 and 4 of a data file (these two extra values are
 read in as ylow and yhigh values for the y values in column 2) or (2)
 from column 3 (this value is a delta y).  If you're using the 'autox'
 keyword you need one column less than specified above since the x
 values will be assigned automatically.

 Two types of error bars may be drawn:  type 1 is simply a vertical
 line spanning the error;  type 2 has to tic marks parallel to the
 x-axis, the size of the symbol, like a bracket.  The default is type 2.

 For axes specified as logarithmic, the log of the data values is
 plotted.  The log of absolute values is plotted.  For zero or negative
 data values, the log of 0.001 is plotted.

 Optionally, a definition may be given on this line as well, for example,
 'plot s=2 cos(x/s)'.

 'noplot' or 'nodata' clears all data points from memory and leaves
 Graphica as if no data points or functions had been entered.

 'plots' by itself shows the currently defined plots, including data,
 functions, smoothed curves, polynomial fits and shaded data.

 If the 'column' command assigned column 3 of a data file to the x-axis
 and column 1 to the y-axis, 'plot x y add points' will generate a graph
 of column 3 versus column 1.

 Examples:

     » plot 'exp.dat'                  # plot data in datafile exp.dat

     » plot 'bar.dat' errorbars 1      # plot error bars

     » plot 'one-y.dat' autox add      # plot a single column with symbols

     » plot data                       # equivalent to 'plot x y connect'

     » data 'oilrate.dat'
     » draw x y
     » plot data step                  # draw a step plot of 'oilrate.dat'

     » map x 0 100 y 0 200             # map the x-axis from 0 to 100
     » draw x y                        # draw the axes
     » plot f 20 80 b(f)               # plot b(f) only from 20 to 80

     » plot sin(x)                     # plot the sine of x

     » plot sin(x) cos(x)              # plot sin(x) and cos(x)

     » plot cos(x) add symbols connect points

     » plot s=0.1, t(x)                # define a variable s, plot t(x)

 where t(x) has been defined previously and is a function of s.

     » noplot                          # clear out any plot information

 Also see COLUMN, FUNCTIONS, MAP, PARAMETRIC, POLAR, SAMPLING and SYMBOLS.
≡plotting
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   plotting sequence <start>,<stop> {{by} <increment>}                │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 If you want the program to plot the data other than in the normal
 fashion (start with the first point and plot all points up to the
 last one), use this command to alter the program's processing loop.
 Given as integers, <start> indicates the first data point to start
 at, <stop> is the last data point to plot and <increment> controls
 which points to pick up within the start-stop range.  The default
 is to plot all points in increments of 1.

 'plotting seq' without arguments shows the current plotting sequence.

 Example:

     » plotting sequence 2,10,2

 plots points 2, 4, 6, 8 and 10.
≡polar
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   polar <function> {connect {points}} {add {symbols}}                │
 └──────────────────────────────────────────────────────────────────────┘

 Definition:

 This command generates polar plots and is similar to the 'plot'
 command.  You can plot data, functions and data files.  Type PLOT
 for some more details.  'polar' by itself simply gives a list of plots
 made so far.

 There is a dummy variable 't' which can be mapped to specify the range
 of values that will be covered by the function.  Polar plots are
 simple transformations of a function y = f(t) where

       xc = y * cos( t )
 and
       yc = y * sin( t )

 and xc and yc are the transformed values in cartesian coordinates.
 't' can be mapped as follows:

       » map t <tmin> <tmax>

 The default map is 0 to 2*pi.  Polar plots can also be done using the
 parametric function plotting feature.

 Examples:

     » polar .5, 1, 1.5

 plots three circles of the given radius.

     » polar cos(2*x)

 plots a cloverleaf.

 Also see FUNCTIONS, MAP, PARAMETRIC, PLOT, and SYMBOLS.
≡fits
 ┌──────────────────────────────────────────────────────────────────────┐
 │   Curve Fits                                                         │
 └──────────────────────────────────────────────────────────────────────┘

 Graphica curve fit options currently include polynomial and spline
 fitting and smoothing.

 'polyfit' generates an nth degree polynomial least squares fit of the
 current data.  The coefficients of the polynomial are given.

 'spline' is used to interpolate the current data using splines under
 tension.  The spline goes through every data point.

 'smooth' is simply used to draw a "smooth curve through scattered
 data points."  The smooth curve does not necessarily go through any
 data point.

 Spline fitting and smoothing do not produce an equation (unlike
 polynomial fitting, which does).

 Also see POLYFIT, SMOOTH and SPLINE.
≡polyfit
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   polyfit {degree} n {range {min} {max}}                             │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The 'polyfit' command generates an nth degree polynomial least squares
 fit of the current data.  The highest degree possible is 10.

 Optionally, a range of given x values may be provided and Graphica
 will plot the least squares fit from min to max only.

 Polynomial fits apply to the LATEST data set, that is, you can't fit a
 polynomial to the last polynomial, only to a set of previously entered
 data points or function.

 'polyfit' by itself shows the current polynomial fitting and correlation
 coefficients.

 The number of points plotted on the polynomial fit can be changed by
 the 'sampling' command.

 Examples:

     » polyfit degree 2
     » polyfit range 20 30
     » polyfit 5
     » polyfit

 Also see FIT, SAMPLING, SMOOTH and SPLINE.
≡postscript
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   terminal postscript {color} {bw} {font fontname} {level2}          │
 │   terminal epsf                                                      │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The PostScript device driver can output color commands.  The default
 is gray-scale output.  Black & white output can be forced through the
 'bw' switch.

 Although Level 1 PostScript is the default, Level 2 output can also
 be generated.  There is only one Level 2 feature active at the moment
 (setfont).

 The same switches ('color', 'bw', 'font' and 'level2') apply to the
 Encapsulated PostScript driver (epsf) and work in the 'dump' command.

 Examples:

     » term post
     » dump post "graph.ps" color    # used in color postscript printers
     » dump post "graph.ps" bw       # forces black & white output

 See DUMP, OUTPUT and TERMINAL.
≡pwd
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   pwd                                                                │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The 'pwd' command prints the name of the current working directory.

 Example:

     » pwd

 would print out C:\WORK, for example, on DOS systems or /usr/work in UNIX.
≡recall
≡editing
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   recall                                                             │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 On some systems (COHERENT and DOS), Graphica is compiled with a feature
 called last-line editing and recall.  In that case, the arrow keys on
 the keypad can be used to edit mistyped commands or to recall previous
 command lines.

 Instead of retyping an entire line, simply hit the up-arrow or down-
 arrow keys to recall previous input lines.  Then you can move the
 cursor over using the left and right-arrow keys and edit the line.
 The arrow keys on the keypad work on copies of the previous input
 lines, which have been saved in a moderately sized input buffer.
 Here is a brief description of the arrow key functions:

     ^N  or  up arrow          recall previous line
     ^P  or  down arrow        recall next line
     ^B  or  left arrow        move left one character
     ^F  or  right arrow       move right one character
     ^A  or  home              move to beginning of line
     ^E  or  end               move to tend of line
     ^U  or  esc (esc)         cancel current line
     ^H  or  del               delete character at cursor
             backspace         delete character left of cursor

     ^K      kills from current position to the end of line
     ^D      deletes the current character, or EOF if line is empty
     ^L/^R   redraw line in case it gets trashed
     ^W      kills last word

 RETURN returns the entire line regardless of the cursor position.

 On systems without the last-line editing and recall feature, the 'recall'
 command gives a list of the last 10 user input lines for review.

 Example:

     » recall

 would give out a list such as:

     paper size 11 by 8.5
     subplot 2 3 6 7
     frame
     draw x y
≡rectangle
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   rectangle {from <x1>,<y1>} {to <x2>,<y2>}                          │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 This command generates a rectangle with its lower left hand corner
 at <x1>,<y1> and its upper right hand corner at <x2>,<y2>.

 Entering 'rectangles' by itself simply shows the currently defined
 rectangles.

 Example:

     » rectangle from 1.0,2.0 to 3.0,4.0

 Also see ARROW, CIRCLE, LABEL, LEGEND and LINE.
≡revisions
 ┌──────────────────────────────────────────────────────────────────────┐
 │   Revision History                                                   │
 └──────────────────────────────────────────────────────────────────────┘

 18 December 93 - Added linestyles to the Lotus 1-2-3 PIC driver.

 17 December 93 - Added left division \ to the set of internal functions.

 9 December 93 - The '[' character (left square bracket) is no longer
   allowed as a comment delimiter.

 30 November 93 - Fixed a bug with the Lotus 1-2-3 PIC driver.

 29 November 93 - Prevented 'spline range xmin xmax' from exceeding
   the maximum x data point.

 25 November 93 - Added the following probability distribution
   functions:  Binomial, Complemented Binomial, Inverse Binomial,
   Negative Binomial, Complemented Negative Binomial, Chi-square,
   Complemented Chi-square, Inverse of Complemented Chi-square, F,
   Complemented F, Inverse of Complemented F, Gamma, Complemented
   Gamma, Poisson, Complemented Poisson, Inverse Poisson and Student's t.
   Changed 'beta' to 'ibeta', 'normal' to 'ndtr', and 'inormal' to
   'ndtri'.  Type HELP PROBABILITY for details.

 23 November 93 - Added F1 ('help') and F10 ('show') function key support.

 14 November 93 - Changed version to 2.5.

 3 November 93 - Added LaserJet II, DeskJet 500 and LaserJet 4 drivers.
   Type HELP LASERJET.

 29 October 93 - Added smoothing of data points.  Type HELP SMOOTH.
   Changed the default symbol size to 0.1 inches (instead of 0.17).

 25 October 93 - Added nine more Bessel functions: besi0, besi1, besin,
   besjn, besk0, besk1, beskn and besyn.  Type HELP BESSEL.

 21 October 93 - Added the following built-in functions: beta, gamma,
   igamma, ierf, inormal, normal, and rand.  Type HELP FUNCTIONS.

 19 October 93 - Added the 'what' command to the Coherent version to list
   all the *.plt files in the current directory.

 18 October 93 - Added last-line editing and command recall to the
   Coherent version.

 1 October 93 - Added checks when reading data in from a data file to
   prevent memory overflows and lockups in the DOS version using Borland's
   compiler.

 25 September 93 - Fixed a little bug which screwed up the prompt when
   shelling out to DOS a second time.

 24 September 93 - Added hardware font sizes to the Coherent version.

 20 September 93 - Fixed a bug that showed the last DOS screen immediately
   after pressing any key at the introductory Graphica screen.

 16 September 93 - Added 'lineto' and 'moveto' commands.

 15 September 93 - Corrected a problem with the timestamp printed out
   in hpgl mode when the character size, ratio or gap where changed.

 14 September 93 - Added 6 filled symbols to the bgi and HPGL2 drivers.
   HPGL can produce only a filled square.  Working on filled symbols for
   the PostScript driver.

 12 September 93 - Changed version to 2.44.  The line continuation symbol
   ';' can now also be used in script files as well as interactively.

 10 September 93 - Fixed some bugs related to the 'location' command
   when used with units other than inches.  Added 'ufactor' to the set of
   pre-defined constants.  Type HELP WHO.

 8 September 93 - Added an optional range specification to the 'plot'
   command.  Type HELP PLOT for details.

 7 September 93 - Changed version to 2.43.  "Beautified" the help file.
   If the environment variable GRAPHELP is not set, Graphica will look
   for the help file in any of the directories currently in your DOS
   path.  If the file is not found, you won't have any help on-line.

 6 September 93 - Program froze up when trying to delete labels, arrows,
   circles, etc.  Fixed this bug.

 5 September 93 - Added a 'rotate' switch to the x,y,y2 and x2-label
   commands to draw them at 180 degrees.  Type HELP PLOT for details.

 4 September 93 - Added color and hardware font support to the PIC
   driver.  PIC still doesn't support line widths.

 30 August 93 - Added color and hardware fonts to the PostScript driver.
   For details type HELP POSTSCRIPT and HELP TERMINAL.

 20 August 93 - Fixed some bugs relative to the thickness of characters
   drawn with the 'legend' and 'label' commands.  Thoroughly tested and
   fixed Graphica's operation in video modes other than VGA.  New data
   input routine ignores labels in data files (see DATA).

 17 August 93 - Whenever you shell out to DOS, a temporary prompt is
   shown telling you to type EXIT to return to GRAPHICA.  Activated the
   Hercules video driver and fixed some color-related bugs.  Slightly
   changed the behavior of the legend block command (see HELP LEGEND).

 10 August 93 - Added a 'clc' command to clear the text screen.

 15 July 93 - Changed version to 2.42.

 13 July 93 - Fixed a bug related to the power function (wasn't raising
   to integer powers correctly under Coherent).  Also fixed a bug in the
   Coherent cbm (coherent bitmap graphics) driver not resetting the line
   style after loading a second load file.

 13 July 93 - After Graphica detects an error with a script file on the
   command line, it stays on line for further processing instead of
   bailing out to the OS command line.

 7 July 93 - Added the 'what' command listing all .plt files in the
   current directory.

 1 July 93 - Started working on the 'polar' command to make polar plots.

 25 June 93 - Changed version to 2.41.

 22 June 93 - Found and fixed a serious bug with the font routines.

 20 June 93 - Changed code to handle errors when dynamically loaded font
   files are not found.

 5 June 93 - Added 10 dynamically loaded software fonts to the registered
   version.  See DEMO5 and DEMO6 for how the new fonts look.

 2 June 93 - Added code to dynamically load software fonts from disk, thus
   reducing the executable size considerably.  Changed version to 2.4.

 14 May 93 - Added linestyles to the Coherent version.  Soon linewidths.

 20 April 93 - Changed some code to prevent errors from occurring when
   changing terminals from bgi to (some other terminal) back to bgi.

 19 April 93 - Started work on the LaTeX driver.

 17 Apr 93 - Added the capability of sending output to the printer port
   in the DOS version.  If you have a printer connected to that port, for
   example, you can send PostScript output directly to the printer (without
   having to DUMP to a file and then send it later.)  Type HELP OUTPUT.

 14 Apr 93 - Finished adding on-screen color graphics to the Coherent
   version.  Still need to add linestyle and linewidth.  It also has a
   simple hardware font.

 10 Apr 93 - Worked on the Coherent version for quite some time trying
   to fix miscellaneous bugs and core dumps.

 2 Apr 93 - Got rid of the 'show' command for showing status.  Now
   simply entering a command by itself will show its status.  'show' by
   itself works just like before, i.e. it displays whatever you've
   plotted so far on the screen or output device.  Changed the meaning
   of the 'axes' command.  It no longer draws those axes that have been
   mapped.  Now it simply tells what axis types you've got.

 20 Mar 93 - Added asinh, acosh and atanh to the set of built-in
   functions.  Type HELP FUNCTIONS.

 20 Mar 93 - The 'print' command has been taken out.  If you want to
   evaluate functions or expressions, simply enter them at the Graphica
   command line.  Type HELP EXPRESSIONS.

 20 Mar 93 - Added 'searchpath' logic to the DOS version.  Graphica
   will try to locate any script or data file entered with the 'load' or
   'data' commands in the current DOS search path, not just in the current
   working directory.  You can also simply enter a script filename at the
   Graphica command line and Graphica will try to determine if it exists
   in the current search path, try to 'load' it and execute commands from
   it.  Type HELP LOAD.

 20 Mar 93 - Changed the environmental variable GRAPHICA to GRAPHINI.
   It now should contain the full path to the start-up filename,
   including the filename itself, just like in GRAPHELP.  Type HELP STARTUP
   and HELP ENVIRONMENT.

 20 Mar 93 - Changed version to 2.3.

 17 Mar 93 - Pressing any key will cancel the introductory graphics
   screen.  Also, in batch mode plotting, the introductory screen does
   not show up.  Added a symbol type of 0 or 'dot' for plotting lots of
   data with just tiny dots.  Type HELP SYMBOLS.

 13 Mar 93 - Renamed this help file to GRAPHICA.FIL to make things less
   confusing for the development of the windows version.  The compiled
   windows version help file will be called GRAPHICA.HLP.

 10 Mar 93 - Corrected some logic in the handling of units (in, cm,
   mm).  Repositioned the mouse location to the bottom right on DOS
   systems.  Also added a 'nodisplay' command to not show the location
   of the mouse cursor.  The mouse cursor shows up right above the
   location display on the lower right hand corner of the screen.

 3 Mar 93 - Added a 'default' command to reset various parameters to
   their default values.  Type HELP DEFAULT.

 2 Mar 93 - Added a .PG command to the HPGL driver when a 'clear' command
   is given.  This ejects the page on some plotters and loads a blank one.

 2 Mar 93 - Fixed the way log labels were plotted when noexponent was
   the default.  Now, regardless of the length of the label, you'll
   always get the full label, i.e.  0.00000001 instead of 10 ** -8 as
   before.  The old behavior would plot a log axis like (10**-4, 0.001,
   0.01, 0.1, 1, 10, 100, 1000, 10**4, 10**5) which was not consistent.
   With 'exponent' you still get the powers of 10 all the time.

 1 Mar 93 - You can now "remap" an axis even after you've plotted
   data and that axis.  The new mapping will be reflected in the last
   plot data set and the last axis of that type plotted.  Try plotting
   some data and changing the map of an axis to see the effect.

 1 Mar 93 - Reduced the mask area around the legend to the actual
   framing area.  Fixed the 'audit' command to work properly.  Fixed a
   bug that would show up when inputing data interactively and
   specifying 'end' before actually entering points.  Solid lines are
   now plotted on decade boundaries in log axes.

 28 Feb 93 - Fixed some problems with polynomial and spline fitting.
   Modified the command 'polyfit' to list all the polynomial fitting and
   correlation coefficients.  Polynomial and spline fits apply to the
   "latest" data set, that is, you can't fit a spline to the last spline,
   only to a set of data points or function.  Fixed other problems with
   multiple polyfit plotting.

 26 Feb 93 - The letters C and c will no longer be comment flags.
   You can continue to use # to make comments in script files or
   when entering data on the > prompt.  (I was having trouble defining
   functions like c(x)= etc.)

 24 Feb 93 - Fixed a problem with the Coherent version of the 'cd'
   command.  Now, you can also enter filenames with the 'load' command
   or directories in 'load' without quotes around them.

 23 Feb 93 - After batch processing script files on the OS command line,
   Graphica now remains online for further interactive processing.

 19 Feb 93 - Graphica returns to the command line after 'dumping' plots
   to a file rather that redrawing the entire plot.  You can still redraw
   what you've got by specifying 'show' after dumping.

 14 Feb 93 - Fixed a small quirk when entering two commands on the
   same line separated by ';'.  For example, when entering 'draw x ;
   draw y' you would have to press a key once before you could see the
   second axis.  Now Graphica recognizes the second command on the same
   line and waits to process graphics until all commands have been parsed.

 10 Feb 93 - Fixed a problem with the legend mask when plotting on a
   non-raster device.  Optimized axis drawing with a grid.  Now there is
   less pen changing when plotting on a plotter.  Fixed a bug happening
   when 'dump' was entered all by itself in a command line.

 9 Feb 93 - Added 2-variable function specification and fixed a bug
   reading in dummy variables.

 8 Feb 93 - Added 'reverse' logarithms, in other words, you can plot log
   scales going from 1000 to 1, for example (the axis minimum is 1000 on
   the left and the maximum is 1 on the right).

 5 Feb 93 - Fixed a problem with 'character'.  Changed the help file
   system a little bit so you get a list of subtopics when you've entered
   an incorrect keyword.

 3 Feb 93 - Changed to version 2.2 and uploaded it to CompuServe.

 2 Feb 93 - Finally got around fixing the legend routines.  The legend
   lines weren't quite aligned when center- or right-justified.  Added a
   new keyword 'flat' to draw non-stacked legends Lotus 1-2-3 style.  Check
   out the 'legend.plt' 'and flat.plt' scripts file to see how it works.

 31 Jan 93 - Added the error and complementary error functions to the
   set of built-in functions.  Type HELP FUNCTIONS.

 30 Jan 93 - Wrote a "getch" function for COHERENT so you can press any
   key to continue rather than having to press return.  Check out the new
   help system.

 29 Jan 93 - New feature: you can now have several curves in a data file
   by separating the data by blank lines.  See help on FILE and the
   'world.plt' example script file.

 28 Jan 93 - Changed the default color to green.

 22 Jan 93 - Fixed BIG BUGS when error bar and probability plotting.

 21 Jan 93 - Fixed a tiny little bug with the memory allocation code
   in the recall function (DOS version).

 20 Jan 93 - Changed version to 2.1.

 20 Jan 93 - Changed code in the COHERENT and DOS versions to read in only
   help keywords when requesting help.  The help text is read in from the
   help file as needed.  The new scheme reduces the memory requirements on
   PCs.  Now you can load in bigger script files!

 14 Jan 93 - Ported Graphica to a Sun 4 workstation (no graphics yet).
   Cleaned up the code a little bit, especially dealing with include files.
   Should be easier to port to many platforms now.

 3 Jan 93 - Changed the mouse routines in the DOS version to use a
   software cursor (faster than using getimage/putimage).

 2 Jan 93 - Added code to save text screen before going into graphics in
   the DOS version.  This way when you get back to text mode, previous text
   will still be visible.

 23 Dec 92 - Added the capability of sending output to com1 in the DOS
   version.  If you have a plotter connected to that communications port,
   for example, you can send hpgl output directly to the plotter (without
   having to DUMP to a file and then use COPY FILE COM1: at the DOS prompt.)

 23 Dec 92 - Fixed a little buglet when changing terminal types and output
   was sent to (stdout).  'output' now shows the correct output.

 14 Dec 92 - Added further functionality to the 'format' command by
   allowing user-defined tic labels.  Type HELP FORMAT.

 14 Dec 92 - Added the 'square-root' type to the family of axis types.

 8 Dec 92 - Fixed a bug in the help command.  You can abort help by
   pressing q/Q/ESC.  With the bug, the next help command was invalid.

 24 Nov 92 - Added two fonts to the Coherent version, simplex script and
   complex script.

 17 Nov 92 - Fixed a bug with the probability scale.  It wasn't drawing
   the numeric labels in the right place when plotting an x2 or y2 axis.

 12 Nov 92 - Fixed bugs in the 'mask' command.  Circles and rectangles
   are now being masked correctly.

 9 Nov 92 - Released version 2.0 to Simtel.
≡range
 ┌──────────────────────────────────────────────────────────────────────┐
 │   range                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 This command shows the input data range (max and min) of each column,
 if any.
≡sampling
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   sampling <expression>                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 Graphica always tries to plot functions as smooth curves.  It is
 impossible to sample the infinite number of points that would be
 needed to reproduce a given function exactly.  Since the function is
 only sampled at a limited number of points, Graphica can sometimes
 miss features of the function.  By increasing the sampling rate, you
 can make Graphica sample your function at a larger number of points.
 Of course, the larger the sampling rate, the longer it will take
 Graphica to plot any function, even a smooth one.

 The sampling rate is changed by the 'sampling' command.  By default,
 sampling is set to 150 points.  A higher sampling rate will produce
 more accurate plots, but will also take longer.

 For example, the function sin(1/x) wiggles infinitely often when x
 is near zero.  As a result, there are slight glitches in the plot.
 Increasing the sampling rate will reduce the number of glitches.

 Entering 'sampling' by itself simply shows the current sampling rate.

 'sampling' also affects the number of points plotted when polynomial
 fitting, spline fitting or smoothing.

 Example:

     » sampling 200

 Also see FIT, FUNCTIONS, PARAMETRIC, PLOT, POLYFIT, SPLINE and SMOOTH.
≡save
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   save                                                               │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The 'save' command creates a file called 'session.log' containing a few
 basic settings of your graphica session.  It will not entirely reproduce
 complicated graphs.

 Example:

     » save
≡shade
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   shade {spacing} {angle} <value> {mode} <integer>                   │
 │         {(no)closure}                                                │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The 'shade' command allows the user to shade a specified polygon.
 'spacing' is the vertical distance between shade lines in default
 user units.

 Optionally, a shade 'angle' may be specified.  This angle is measured
 from the horizontal.  The sign convention for the direction of rotation
 is as follows:

     + clockwise
     - counterclockwise

 'mode' indicates the following:

     mode = 1 - shade and outline (this is the default)
     mode = 2 - shade polygon only
     mode = 3 - outline polygon only

 The 'closure/noclosure' keyword is used to specify whether Graphica
 should draw a line making the polygon a closed one or not.  This
 keyword is only active when mode is 1 or 3.  The default is 'noclosure'.

 Example:

     » shade angle 35.0 mode 1
≡shell
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   shell                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The shell command spawns an interactive shell.  Use this option to
 access the operating system prompt and execute commands or run other
 programs.  When shelling out to the operating system, you can execute
 any command or application.  To return to Graphica: type EXIT at the
 command line (under DOS);  type control-d (under Coherent);  do
 stop/id=xxx, where xxx is your subprocess ID (under VAX/VMS).

 A single shell command may be spawned by preceding it with the $
 character on the very first position of a command line.  Control will
 return immediately to Graphica after this command is executed.

 Examples:

     » shell

 spawns a shell to the operating system.  Type EXIT to return to Graphica.

     » $dir

 prints a directory listing and then returns to Graphica without waiting.

 Also see DELETE, DIR, TYPE and WHAT.
≡show
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   show                                                               │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

    The SHOW command redraws existing plots on your screen.
≡smooth
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   smooth {n} {range {min} {max}} {(no)spline}                        │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 Data smoothing is used simply as a graphical technique, to guide the
 eyes through a forest of scattered data points.  Graphica removes any
 linear trend, uses a Fast Fourier Transform to low-pass filter the
 data and reinserts the trend at the end.

 If the total number of points is smaller than the current sampling
 rate, Graphica generates a spline curve through the resulting smooth
 points.  You can force a spline fit anyway, by specifying 'spline'
 on the command line.  The number of points plotted on the smooth
 spline curve can be changed by a previous 'sampling' command.  Or,
 you can prevent Graphica from drawing a spline fit regardless of the
 total number of points by specifiying 'nospline'.

 The user-specified constant 'n' gives the number of points over which
 the data should be smoothed.  A value of zero gives no smoothing at
 all.  If 'n' is not specified, the default is 5.

 Optionally, a range of x values may be provided and Graphica will
 smooth data points from min to max only.

 Smoothing applies to the LATEST data set, that is, you can't smooth
 a smoothed curve, only a set of previously entered data points or
 function.

 Examples:

     » smooth 10
     » smooth range 20 30
     » smooth 8 spline
     » smooth nospline

 Also see FIT, POLYFIT, SAMPLING and SPLINE.
≡spline
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   spline {plot} {tension {value}} {range {min} {max}}                │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The 'spline' command is used to interpolate the current data using
 splines under tension.  The produced data curve is a spline under
 tension, which is somewhat "tighter" than a cubic spline, and less
 likely to have spurious inflection points.  The cubic spline
 interpolator will produce a smooth curve through (x,y) data pairs,
 even if their variation is quite complicated.

 The tension factor indicates the curviness desired for the line
 produced by the cubic spline.  A tension in the interpolating curve
 of 50 gives almost a polygonal line;  a tension of 0.01 gives almost
 a cubic spline.  The default of 2.0 will produce a smooth curve in
 most cases.  For very erratic data it may be necessary to tighten
 up the tension factor to 5 or 6 to adequately follow the data points.

 Optionally, a range of given x values may be provided and Graphica
 will interpolate from min to max only.

 Spline fits apply to the LATEST data set, that is, you can't fit a
 spline to the last spline, only to a set of previously entered data
 points or function.

 The number of points plotted on the spline fit can be changed by the
 'sampling' command.

 Examples:

     » spline plot tension 10
     » spline range 20 30

 Also see FIT, POLYFIT, SAMPLING and SMOOTH.
≡subplot
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   subplot {size/area} <xleft> <ybottom> <xright> <ytop>              │
 │           {default}                                                  │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The subplot area is also referred to as soft clip.  The actual graph
 resides in the subplot area but other graphic elements can be drawn
 outside the subplot area.

 The 'subplot' command defines the region on the paper where the plot
 is drawn.  By default, the subplot area is set to a rectangle of
 about 60% of the paper size.  The (xleft,ybottom) pair sets the
 coordinates of the left bottom corner of the subplot area, while the
 (xright, ytop) pair sets the coordinates of the top right hand corner
 of the plotting region.  If subplot default is specified, the subplot
 area size will be reset to its default size.

 Data points and curves are drawn or plotted on a grid space formed
 by Cartesian coordinate axes.  The horizontal line is the x-axis and
 the vertical line is the y-axis.  These axes are within the subplot
 area or plotting region.

 Entering 'subplot' by itself simply shows the current subplot area.

 Example:

     » subplot area 2.0,2.0 9.0,7.0
≡subscript
≡superscript
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   subscript {size} <value>                                           │
 │   superscript {size} <value>                                         │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 These commands set the subscript and superscript sizes in default units.
 The default values are 0.15 inches.

 Example:

     » subscript size 0.15
     » superscript size 0.15

 Also see CHARACTER FONT, CHARACTER GAP, CHARACTER RATIO, CHARACTER SIZE,
 CHARACTER SLANT and TEXT.
≡symbol
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   symbol <code>/<name> size <value>                                  │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 Defines the symbol to use in displaying data points.  Mnemonic codes
 may be used to specify a symbol.  You have a choice of 16 standard
 graphics symbols and a dot:
                                   (filled symbols)
      0 - dot
      1 - square                    11 - fsquare
      2 - circle                    12 - fcircle
      3 - triangle                  13 - ftriangle
      4 - diamond                   14 - fdiamond
      5 - itriangle (inv triangle)  15 - fitriangle
      6 - hourglass                 16 - fhourglass
      7 - plus
      8 - cross
      9 - star
     10 - pdiamond (plus within a diamond)

 The default is a square ('symbol 1' or 'symbol square').  The symbol
 size is specified as the height of the current symbol in default units.
 The default symbol size is 0.17 inches.

 If you specify 'symbol 0' or 'symbol dot', no markers will be plotted
 at each point location, just a tiny point the size of a pixel, so you
 can plot lots of data.

 Entering 'symbol' by itself simply shows the current symbol type and
 size.

 (Filled symbols work only on certain hardware devices.  Software symbol
 fill is under development.)

 Examples:

     » symbol square size 0.2
     » symbol 3
     » sym 0
≡terminal
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   terminal {<terminal-type>}                                         │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 Graphica supports many different graphics devices.  Use this command to
 select the type of device for which Graphica will produce output.

 If <terminal-type> is omitted, Graphica will show the currently defined
 output terminal and list the available terminal types.  <terminal-type>
 may be abbreviated.

 Use 'output' to redirect this output to a file, device or port.

 Examples:

     » terminal hpgl
     » terminal

 would print out the following:

 available terminal types:
            unknown  Unknown terminal type - not a plotting device
                bgi  IBM PC/Clone with a Hercules/CGA/EGA/VGA graphics card
               epsf  Encapsulated PostScript Graphics Language
              epson  Epson LX-800, Star NL-10, NX-1000, etc.
               hpgl  HPGL Graphics Language and HP7475 plotter
              hpgl2  HPGL Graphics Language and HP7550 plotter
                pic  Lotus 1-2-3 PIC Graphics Format
         postscript  PostScript Graphics Language

 and possibly (depending on the version you have) any of the following:

             apollo  HP Apollo Domain Workstation - direct mode
                cbm  Coherent Bitmap Graphics
           kercolor  Kermit-MS color tek40xx terminal emulator
            kermono  Kermit-MS monochrome tek40xx terminal emulator
              latex  LaTeX picture environment
                qms  QMS Laser Printer
             raster  Raster Technologies Model One terminal
            tek40xx  Tektronix 4010 and most TEK emulators

 Notes on some of the graphics formats:

 The software fonts will look identically whether you use hpgl, PIC,
 PostScript or any other driver.  The only difference comes from the
 slight resolution difference in the formats.  The standard hpgl
 resolution is 10365 by 7962 pixels.  The Lotus 1-2-3 PIC format has
 a fixed resolution of 3200 by 2311 pixels.  The PostScript driver
 outputs graphic information at a resolution of 7920 by 6120 pixels.

 The hpgl, PIC and PostScript drivers output portrait files by
 turning the paper around 90 degrees.  An hpgl graph will come out
 alright on an actual HP plotter (which has its paper always in the
 landscape orientation).  If you need to import the file into a
 program that can read any of these formats, you'll have to rotate
 the plot back a quarter turn.

 The Lotus 1-2-3 PIC format should not be confused with the PC Paint
 Plus format, PPIC or with Dr. Halo PIC format.  Some programs only
 look at the file extension instead of looking inside the file to
 determine what type of graphics information is in it.  For example,
 the graphics viever VPIC won't read PIC files generated by Graphica
 (because it thinks it's something else).  WordPerfect for DOS and
 Word for Windows will read Graphica PIC files without a hitch.

 Only the PostScript driver supports line widths.

 See DUMP, OUTPUT and POSTSCRIPT.
≡tics
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   tic {size} <major value> <minor value> {<direction>}               │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 All axes are marked off in equal segments with tic marks.  The values
 major and minor determine the size of the major and minor tic marks.
 The defaults are 0.16 and 0.09 inches for the major and minor tic marks,
 respectively.

 By default, tics are drawn inwards from the border on all four sides.
 The 'tic' command can be used to change the tics to be drawn outwards.
 <direction> may be in, out or nothing (which is the same as in).

 Entering 'tics' by itself simply shows the current tic size and direction.

 Example:

     » tic size 0.1 0.06
     » tics in
≡timestamp
≡notimestamp
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   timestamp                                                          │
 │   notimestamp                                                        │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 This command toggles the timestamp on and off on a non-screen plot.
 The timestamp is simply a message drawn near the bottom of the page as
 follows:

     Graphica version 2.2 Thu Feb 11 11:34:14 1993

 'timestamp' activates printing of the message ; 'notimestamp' deactivates
 it.  The default is ON.  You may put a 'notimestamp' command in your
 'graphica.ini' initialization file.

 Examples:

     » timestamp
     » notimestamp

 Also see STARTUP.
≡type
≡more
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   type <file>                                                        │
 │   more <file>                                                        │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The 'type' command displays the contents of a file.  Pathnames, wildcards,
 and drive designators may be used in the usual way for your operating
 system.  Other operating system commands can be issued using the $
 character on the very first position of a line followed by a command.
 'more' is the UNIX version of the command.

 Examples:

     » type script.plt

 lists the ASCII file script.plt.

     » type foo

 lists the ASCII file foo.

 Also see DEL, DIR, SHELL and WHAT.
≡units
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   units <unit type>                                                  │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 It is sometimes desirable to use units other than inches, i.e., the
 metric system, with Graphica.  To change the unit of measure for
 parameters which are usually given in inches use the unit command.
 This command defines the units to be used in subsequent commands which
 represent a length or position normally supplied in inches, such as in
 paper size, subplot area, etc.

 The <unit type> may be 'in', 'cm' or 'mm'.

 Entering 'units' by itself simply shows the current units of measure.

 Changing the units of measure also changes the built-in variable
 'ufactor'.

 Example:

     » units cm

 See VARIABLES.
≡view
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   view                                                               │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 Retracts the pen and advances the paper on a pen plotter to view the
 graph fully.  This command is similar to pushing the VIEW button on
 Hewlett-Packard HP7475 or HP7550 plotters.

 Example:

     » view

 would move the plotting paper outward into view.
≡x
≡y
≡x2
≡y2
≡logarithmic
≡linear
≡sqr
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   {x,y,y2,x2} {linear,logarithmic,probability,sqr}                   │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 With this command, the kind of axis to be plotted may be specified, as
 follows:

 linear - specifies a linear axis.  A linear scale is a standard base 10
 numeric scale.  This is the default.

 logarithmic - specifies a log axis.  A log scale is a base 10
 logarithmic scale.  If a regression has been performed, the values for
 that particular axis are logarithmic.  Given the mapped range for an
 axis, the logarithmic range for that axis will be determined
 automatically.  If an axis is to be logarithmic, there is no need to
 specify the number of divisions or the format.  If the range is
 negative as specified in a map command, Graphica automatically converts
 it to positive.  Zero values for min or max will cause the log axis to
 begin at 0.001.

 probability - a probability scale is the inverse of the Gaussian
 cumulative distribution function.  Thus the graph of the sigmoidally
 shaped Gaussian cumulative distribution function on a probability scale
 will be a straight line.

 Probabilities are expressed as a percentage so that the range of the
 scale is from 0 to 100.  The minimum and maximum values that a
 probability axis can take in Graphica are 0.01 and 99.99.  A probability
 axis label could be specified as something like "cumulative frequency, %".

 sqr - square-root axis.  Used in some engineering applications.  A square
 root scale is based on the square root of the axis in question.

 Examples:

     » x lin
     » y log
     » x2 pro
     » x sqr
≡xlabel
≡ylabel
≡x2label
≡y2label
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   {xlabel,x2label,ylabel,y2label} 'string' {rotate}                  │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 This command draws a centered label for that axis.  The label text must
 be enclosed in single or double quotes.  All labels are drawn using the
 current character font and size.  The label bottom command is equivalent
 to the xlabel command.  Likewise, the 'label top', 'left', and 'right'
 commands are equivalent to the 'x2label', 'ylabel' and 'y2label' commands.

 The ROTATE switch turns the labels around 180 degrees.  This may
 become especially useful when drawing the y2-label (some people prefer
 the y2-label to "face" left rather than right).

 Examples:

     » xlabel 'This is the x-axis label'
     » ylabel 'This is the y-axis label'
     » y2label 'rotated y2-label' rotate
≡expressions
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   <expression>                                                       │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 You can determine the value of expressions or variables by just typing
 the expression or variable at the » prompt.

 In general, any mathematical expression accepted by C, FORTRAN, Pascal,
 or BASIC is valid.  The precedence of these operators is determined by
 the specifications of the C programming language.  White space (spaces
 and tabs) is ignored inside expressions.

 Complex variables may be expressed as {<real>,<imag>}, where <real> and
 <imag> must be numbers.  For example, {3,2} represents 3 + 2i; {0,1}
 represents 'i' itself.  The curly braces are explicitly required.

 Examples:

     » 2*3

 would print out '2*3 = 6'

     » 30+2*2

 would print out '30+2*2 = 34'
≡complex
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   Complex Variables                                                  │
 └──────────────────────────────────────────────────────────────────────┘

 Complex variables may be expressed as {<real>,<imag>}, where <real> and
 <imag> must be numbers.  For example, {3,2} represents 3 + 2i; {0,1}
 represents 'i' itself.  The curly braces are explicitly required.

 Also see EXPRESSIONS and FUNCTIONS.
≡expressions functions
≡functions
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   functions                                                          │
 └──────────────────────────────────────────────────────────────────────┘

 All functions in Graphica accept integer, real, and complex arguments,
 unless otherwise noted.

 The 'functions' command by itself lists all user-defined functions and
 their definitions.

 Graphica also supports the following special functions:

 Gamma function                                     y = gamma( x )
 Natural logarithm of gamma function                y = lgamma( x )

 Incomplete gamma integral                          y = igamma( a, x )
 Complemented incomplete gamma integral             y = igamc( a, x )
 Inverse of complemented incomplete gamma integral  x = igami( a, y )

 Incomplete beta integral                           y = ibeta( a, b, x )
 Inverse of incomplete beta integral                x = ibetai( a, b, y )

 Error function                                     y = erf( x )
 Complementary error function                       y = erfc( x )
 Inverse error function                             x = ierf( y )

 Also see VARIABLES.
≡expressions functions abs
≡functions abs
≡abs
 ┌──────────────────────────────────────────────────────────────────────┐
 │   abs                                                                │
 └──────────────────────────────────────────────────────────────────────┘

 abs(z) returns the absolute value of the real or complex number z.
 The returned value is of the same type as the argument.  For complex
 arguments, abs(z) returns the complex modulus (magnitude) defined as
 the length of z in the complex plane:

     sqrt( real(z)**2 + imag(z)**2 )
≡expressions functions acos
≡functions acos
≡acos
 ┌──────────────────────────────────────────────────────────────────────┐
 │   acos                                                               │
 └──────────────────────────────────────────────────────────────────────┘

 acos(z) returns the arc cosine (inverse cosine) of z.  All results
 are given in radians.  For real z, such that abs(z) <= 0.0, the
 result is in the range 0 to π.  Complex results are obtained if
 abs(z) > 1.0, or if z is complex.  The complex arc cosine is defined as:

     acos(z) = -i log( z + i sqrt(1-z**2) )
≡expressions functions acosh
≡functions acosh
≡acosh
 ┌──────────────────────────────────────────────────────────────────────┐
 │   acosh                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 acosh(z) returns the arc hyperbolic cosine (inverse hyperbolic cosine)
 of z.  All results are given in radians.  For real z, such that abs(z) <=
 0.0, the result is in the range 0 to π.  Complex results are obtained if
 abs(z) > 1.0, or if z is complex.  The complex arc cosine is defined as:

     acosh(z) = -i log( z + i sqrt(1-z**2) )
≡expressions functions arg
≡functions arg
≡arg
 ┌──────────────────────────────────────────────────────────────────────┐
 │   arg                                                                │
 └──────────────────────────────────────────────────────────────────────┘

 arg(z) returns the phase angle of a complex number z, in radians.
 The result is always between -π and π.
 For complex z = x + iy = r exp(i theta), the magnitude and phase
 are given by

     r = abs(z)
     theta = arg(z)
≡expressions functions asin
≡functions asin
≡asin
 ┌──────────────────────────────────────────────────────────────────────┐
 │   asin                                                               │
 └──────────────────────────────────────────────────────────────────────┘

 asin(z) returns the arc sine (inverse sine) of z.  All results are
 given in radians.  For real z, such that abs(z) <= 1.0, the result is
 in the range -π/2 to π/2.  Complex results are obtained if abs(z) >
 1.0, or if z is complex.  The complex arc sine is defined as:

     asin(z) = -i log( iz + sqrt(1-z**2) )
≡expressions functions asinh
≡functions asinh
≡asinh
 ┌──────────────────────────────────────────────────────────────────────┐
 │   asinh                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 asinh(z) returns the arc hyperbolic sine (inverse hyperbolic sine)
 of z.  All results are given in radians.  For real z, such that
 abs(z) <= 1.0, the result is in the range -π/2 to π/2.  Complex
 results are obtained if abs(z) > 1.0, or if z is complex.  The
 complex arc sine is defined as:

     asinh(z) = -i log( iz + sqrt(1-z**2) )
≡expressions functions atan
≡functions atan
≡atan
 ┌──────────────────────────────────────────────────────────────────────┐
 │   atan                                                               │
 └──────────────────────────────────────────────────────────────────────┘

 atan(z) returns the arc tangent (inverse tangent) of z.  All results
 are given in radians.  For real z, the result is in the range -π/2 to
 π/2.  If z is complex, the complex arc tangent is returned:

     atan(z) = i/2 log( (i+z) / (i-z) )
≡expressions functions atanh
≡functions atanh
≡atanh
 ┌──────────────────────────────────────────────────────────────────────┐
 │   atanh                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 atanh(z) returns the arc hyperbolic tangent (inverse hyperbolic
 tangent) of z.  All results are given in radians.  For real z, the
 result is in the range -π/2 to π/2.  If z is complex, the complex arc
 tangent is returned:

     atanh(z) = i/2 log( (i+z) / (i-z) )
≡expressions functions ibeta
≡functions ibeta
≡ibeta
 ┌──────────────────────────────────────────────────────────────────────┐
 │   ibeta                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 ibeta(p,q,z) returns the incomplete beta function of the real parts of
 its arguments (p, q>0 and 0<z<1).  If the arguments are complex, the
 imaginary components are ignored.  The function is defined as

                    x
       -            -
      | (a+b)      | |  a-1     b-1
    -----------    |   t   (1-t)   dt.
     -     -     | |
    | (a) | (b)   -
                   0

≡expressions functions ibetai
≡functions ibetai
≡ibetai
 ┌──────────────────────────────────────────────────────────────────────┐
 │   ibetai                                                             │
 └──────────────────────────────────────────────────────────────────────┘

 x = ibetai(a,b,y) returns the inverse of the incomplete beta function
 of the real parts of its arguments (p, q>0 and 0<z<1).  If the arguments
 are complex, the imaginary components are ignored.  Given y, the function
 finds x such that ibeta( a, b, x ) = y.
≡expressions functions ceil
≡functions ceil
≡ceil
 ┌──────────────────────────────────────────────────────────────────────┐
 │   ceil                                                               │
 └──────────────────────────────────────────────────────────────────────┘

 ceil(z) returns the smallest integer greater than z.  For complex
 numbers, ceil returns the smallest integer greater than the real part of z.
≡expressions functions cos
≡functions cos
≡cos
 ┌──────────────────────────────────────────────────────────────────────┐
 │   cos                                                                │
 └──────────────────────────────────────────────────────────────────────┘

 cos(z) returns the cosine of z, where z is in radians.
 For complex z = x + iy, the complex cosine is returned:

     cos(z) = cos(x) cosh(y) - u sin(x) sinh(y)
≡expressions functions cosh
≡functions cosh
≡cosh
 ┌──────────────────────────────────────────────────────────────────────┐
 │   cosh                                                               │
 └──────────────────────────────────────────────────────────────────────┘

 cosh(z) returns the hyperbolic cosine of z, where z is in radians.
≡expressions functions exp
≡functions exp
≡exp
 ┌──────────────────────────────────────────────────────────────────────┐
 │   exp                                                                │
 └──────────────────────────────────────────────────────────────────────┘

 exp(z) returns the exponential function of z (e raised to the power
 of z).  For complex z = x + iy, the complex exponential is returned:

     exp(z) = exp(x) ( cos(y) + i sin(y) )
≡expressions functions erf
≡functions erf
≡erf
 ┌──────────────────────────────────────────────────────────────────────┐
 │   erf                                                                │
 └──────────────────────────────────────────────────────────────────────┘

 erf(x) returns the error function of x.  erf(x) is the integral of the
 normal (Gaussian) probability distribution function from 0 to x.  The
 error function is central to many calculations in statistics.  It is
 defined as:

     erf(x) = 2/sqrt(pi) integral(0,x) exp(-t^2)

 Also see ERFC and IERF.
≡expressions functions erfc
≡functions erfc
≡erfc
 ┌──────────────────────────────────────────────────────────────────────┐
 │   erfc                                                               │
 └──────────────────────────────────────────────────────────────────────┘

 erfc(x) returns the complementary error function of x.  erfc(x) is
 simply 1.0 - erf(x), where erf(x) is the integral of the normal
 (Gaussian) probability distribution function from 0 to x.

    1 - erf(x) =
                             inf.
                               -
                    2         | |          2
     erfc(x)  =  --------     |    exp( - t  ) dt
                 sqrt(pi)   | |
                             -
                              x
 Also see ERF and IERF.
≡expressions functions floor
≡functions floor
≡floor
 ┌──────────────────────────────────────────────────────────────────────┐
 │   floor                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 floor(z) returns the greatest integer less than or equal to z.  For
 complex numbers, floor returns the largest integer not greater than
 the real part of z.
≡expressions functions gamma
≡functions gamma
≡gamma
 ┌──────────────────────────────────────────────────────────────────────┐
 │   gamma                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 gamma(z) returns the gamma function of the real part of z.  For
 integer z, gamma(z+1) = z!.  If z is a complex value, the imaginary
 component is ignored.

 Also see IGAMMA, LGAMMA, IGAMC, IGAMI.
≡expressions functions lgamma
≡functions lgamma
≡lgamma
 ┌──────────────────────────────────────────────────────────────────────┐
 │   lgamma                                                             │
 └──────────────────────────────────────────────────────────────────────┘

 lgamma(z) returns the base e (2.718...) logarithm of the absolute
 value of the gamma function of the argument.

 Also see GAMMA, IGAMMA, IGAMC, IGAMI.
≡expressions functions igamc
≡functions igamc
≡igamc
 ┌──────────────────────────────────────────────────────────────────────┐
 │   igamc                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 igamc(a,x) returns the complemented incomplete gamma integral.  This
 function is defined by

    igamc(a,x)   =   1 - igamma(a,x)

                              inf.
                                -
                       1       | |  -t  a-1
                 =   -----     |   e   t   dt.
                      -      | |
                     | (a)    -
                               x

 Also see GAMMA, IGAMMA, LGAMMA, IGAMI.
≡expressions functions igami
≡functions igami
≡igami
 ┌──────────────────────────────────────────────────────────────────────┐
 │   igami                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 igami(a,y) returns the inverse of the complemented incomplete gamma
 integral.  Given y, the function finds x such that igamc( a, x ) = y.

 Also see GAMMA, IGAMMA, LGAMMA, IGAMC.
≡expressions functions ierf
≡functions ierf
≡ierf
 ┌──────────────────────────────────────────────────────────────────────┐
 │   ierf                                                               │
 └──────────────────────────────────────────────────────────────────────┘

 ierf(z) returns the inverse error function of the real part of z.  The
 error function, erf(x), is the integral of the normal (Gaussian)
 probability distribution function from 0 to x.

 Also see ERF and ERFC.
≡expressions functions igamma
≡functions igamma
≡igamma
 ┌──────────────────────────────────────────────────────────────────────┐
 │   igamma                                                             │
 └──────────────────────────────────────────────────────────────────────┘

 igamma(a,z) returns the incomplete gamma function of the real parts of
 its arguments (a > 0 and z >= 0).  If the arguments are complex, the
 imaginary components are ignored.

 The function is defined by
                               x
                                -
                       1       | |  -t  a-1
    igamma(a,x)  =   -----     |   e   t   dt.
                      -      | |
                     | (a)    -
                               0

 Also see GAMMA and FUNCTIONS.
≡expressions functions imag
≡functions imag
≡imag
 ┌──────────────────────────────────────────────────────────────────────┐
 │   imag                                                               │
 └──────────────────────────────────────────────────────────────────────┘

 imag(z) returns the imaginary part of z as a real number.
≡expressions functions int
≡functions int
≡int
 ┌──────────────────────────────────────────────────────────────────────┐
 │   int                                                                │
 └──────────────────────────────────────────────────────────────────────┘

 int(z) returns the integer part of z, truncated toward zero.
≡expressions functions ln
≡functions ln
≡ln
 ┌──────────────────────────────────────────────────────────────────────┐
 │   ln                                                                 │
 └──────────────────────────────────────────────────────────────────────┘

 ln(z) returns the natural logarithm (base e) of z.  For complex or
 negative z, the complex logarithm is returned:

     ln(z) = ln( abs(z) ) + i atan2( y, x )
≡expressions functions log
≡functions log
≡log
 ┌──────────────────────────────────────────────────────────────────────┐
 │   log                                                                │
 └──────────────────────────────────────────────────────────────────────┘

 log(z) returns the logarithm (base 10) of z.  For complex or
 negative z, the complex logarithm is returned:

     log(z) = log( abs(z) ) + i atan2( y, x )
≡expressions functions rand
≡functions rand
≡rand
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   rand                                                               │
 └──────────────────────────────────────────────────────────────────────┘

 Syntax:

     rand
     rand(0)
     rand(1)

 Description:

 rand(0) returns a pseudorandom number in the interval (0.0,1.0)
 using a uniform distribution.  rand(1) returns a pseudorandom
 number using a normal distribution with mean 0.0 and variance 1.0.

 Entering 'rand' by itself is equivalent to entering 'rand(0)'.

 When Graphica starts up, it takes the time of day (measured in
 small fractions of a second) as the seed for the pseudorandom
 number generator.  Two different Graphica sessions will therefore
 almost always give different sequences of pseudorandom numbers.

 If you want to make sure that you always get the same sequence
 of pseudorandom numbers, you can explicitly give a seed for the
 pseudorandom number generator, using 'seed'.

 Examples:

     » rand(0)
     » plot rand(0) add
     » rand
     » rand(1)

 Also see FUNCTIONS and SEED.
≡seed
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   seed                                                               │
 └──────────────────────────────────────────────────────────────────────┘

 Syntax:

     seed n

 Description:

 'seed' explicitly gives a seed for the pseudorandom number generator.

 Example:

     » seed 321
     » rand
 rand = 0.27789
     » rand
 rand = 0.41721

 To repeat the sequence exactly, reseed the number generator:

     » seed 321
     » rand
 rand = 0.27789
     » rand
 rand = 0.41721

 Also see RAND.
≡expressions functions real
≡functions real
≡real
 ┌──────────────────────────────────────────────────────────────────────┐
 │   real                                                               │
 └──────────────────────────────────────────────────────────────────────┘

 real(z) returns the real part of z.
≡expressions functions sgn
≡functions sgn
≡sgn
 ┌──────────────────────────────────────────────────────────────────────┐
 │   sgn                                                                │
 └──────────────────────────────────────────────────────────────────────┘

 sgn(z) returns 1 if z is positive, -1 if z is negative, and 0 if z is 0.
 If z is a complex value, the imaginary component is ignored.
≡expressions functions sin
≡functions sin
≡sin
 ┌──────────────────────────────────────────────────────────────────────┐
 │   sin                                                                │
 └──────────────────────────────────────────────────────────────────────┘

 sin(z) returns the sine of z, where z is in radians.
 For complex z = x + iy, the complex sine is returned:

     sin(z) = sin(x) cosh(y) - i cos(x) sinh(y)
≡expressions functions sinh
≡functions sinh
≡sinh
 ┌──────────────────────────────────────────────────────────────────────┐
 │   sinh                                                               │
 └──────────────────────────────────────────────────────────────────────┘

 sinh(z) returns the hyperbolic sine of z, where z is in radians.
≡expressions functions sqrt
≡functions sqrt
≡sqrt
 ┌──────────────────────────────────────────────────────────────────────┐
 │   sqrt                                                               │
 └──────────────────────────────────────────────────────────────────────┘

 sqrt(z) returns the square root of z.
≡expressions functions tan
≡functions tan
≡tan
 ┌──────────────────────────────────────────────────────────────────────┐
 │   tan                                                                │
 └──────────────────────────────────────────────────────────────────────┘

 tan(z) returns the tangent of z, where z is in radians.
 For complex z, the complex tangent sin(z)/cos(z) is returned.
≡expressions functions tanh
≡functions tanh
≡tanh
 ┌──────────────────────────────────────────────────────────────────────┐
 │   tanh                                                               │
 └──────────────────────────────────────────────────────────────────────┘

 tanh(z) returns the hyperbolic tangent of z, where z is in radians.
≡expressions operators
≡operators
 ┌──────────────────────────────────────────────────────────────────────┐
 │   Operators                                                          │
 └──────────────────────────────────────────────────────────────────────┘

 All operators in Graphica accept integer, real, and complex arguments,
 unless otherwise noted.  The ** operator (exponentiation) is supported,
 as in FORTRAN.

 Parentheses may be used to change the order of evaluation.
≡expressions operators binary
≡operators binary
≡binary
 ┌──────────────────────────────────────────────────────────────────────┐
 │   Binary Operators                                                   │
 └──────────────────────────────────────────────────────────────────────┘

 The following is a list of all the binary operators and their usage:

         symbol             example              explanation

          **                 a**b                 exponentiation
          *                  a*b                  multiplication
          /                  a/b                  division
          \                  a\b                  left division
          %                  a%b                * modulo
          +                  a+b                  addition
          -                  a-b                  subtraction
          ==                 a==b                 equality
          !=                 a!=b                 inequality
          &                  a&b                * bitwise AND
          ^                  a^b                * bitwise exclusive OR
          |                  a|b                * bitwise inclusive OR
          &&                 a&&b               * logical AND
          ||                 a||b               * logical OR

          (*) Operator requires integer arguments.

 Logical AND (&&) and OR (||) short-circuit the way they do in C.  That
 is, the second && operand is not evaluated if the first is false;  the
 second || operand is not evaluated if the first is true.

 Multiplication must be explicitly noted with the asterisk;  adjacent
 parenthetical terms such as (a+b)(c-4) are not automatically multiplied.

 The left division a\b is equivalent to b/a.
≡expressions operators ternary
≡operators ternary
≡ternary
 ┌──────────────────────────────────────────────────────────────────────┐
 │   Ternary Operators                                                  │
 └──────────────────────────────────────────────────────────────────────┘

 The following is a list of the ternary operator and its usage:

          symbol             example              explanation

           ≡:                 a≡b:c              * ternary operation

          (*) Operator requires an integer argument.

 The ternary operator evaluates its first argument (a).  If it is true
 (non-zero) the second argument (b) is evaluated and returned, otherwise
 the third argument (c) is evaluated and returned.
≡expressions operators unary
≡operators unary
≡unary
 ┌──────────────────────────────────────────────────────────────────────┐
 │   Unary Operators                                                    │
 └──────────────────────────────────────────────────────────────────────┘

     The following is a list of all the unary operators and their usage:

          symbol             example              explanation

           -                  -a                   unary minus
           ~                  ~a                 * one's complement
           !                  !a                 * logical negation
           !                  a!                 * factorial

          (*) Operator requires an integer argument.

 The factorial operator returns a real number to allow a greater range.
≡probability
 ┌──────────────────────────────────────────────────────────────────────┐
 │   Probability Distribution Functions                                 │
 └──────────────────────────────────────────────────────────────────────┘

 Probability distribution functions are used in the mathematics areas of
 probability and statistics.  If an experiment can occur in 'n' mutually
 exclusive and equally likely ways, and if exactly 'm' of these ways
 correspond to an event 'E', then the probability of 'E' is given by

            m
     P(E) = -.
            n

 The probability that the value of a random variable 'X' is less than or
 equal to some real number 'x' is defined as

     F(x) = P(X ≤ x), -∞ < x < ∞
          = integral(-∞ to x) f(x) dx

 where f(x) is called the probability density of the random variable X.

 Graphica implements 20 probability distribution functions.  Refer to
 a good statistics textbook for details.  The functions are:

   Binomial distribution                            y = bdtr( k, n, p )
   Complemented Binomial distribution               y = bdtrc( k, n, p )
   Inverse Binomial distribution                    p = bdtri( k, n, y )

   Negative Binomial distribution                   y = nbdtr( k, n, p )
   Complemented Negative Binomial distribution      y = nbdtrc( k, n, p )

   Beta distribution                                y = btdtr( a, b, x )

   Chi-square distribution                          y = chdtr( df, x )
   Complemented Chi-square distribution             y = chdtrc( v, x )
   Inverse of Complemented Chi-square distribution  x = chdtri( df, y )

   F distribution                                   y = fdtr( df1, df2, x )
   Complemented F distribution                      y = fdtrc( df1, df2, x )
   Inverse of Complemented F distribution           x = fdtri( df1, df2, y )

   Gamma distribution                               y = gdtr( a, b, x )
   Complemented Gamma distribution                  y = gdtrc( a, b, x )

   Normal distribution                              y = ndtr( x )
   Inverse of Normal distribution                   x = ndtri( y )

   Poisson distribution                             y = pdtr( k, m )
   Complemented Poisson distribution                y = pdtrc( k, m )
   Inverse Poisson distribution                     m = pdtri( k, y )

   Student's t distribution                         y = stdtr( k, t )

 Also see BDTR, BDTRC, BDTRI, NBDTR, NBDTRC, BTDTR, CHDTR, CHDTRC,
 CHDTRI, FDTR, FDTRC, FDTRI, GDTR, GDTRC, NDTR, NDTRI, PDTR, PDTRC,
 PDTRI, and STDTR for more details.
≡expressions functions bdtr
≡functions bdtr
≡bdtr
 ┌──────────────────────────────────────────────────────────────────────┐
 │   bdtr                                                               │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 bdtr(k,n,p) returns the sum of the terms 0 through k of the Binomial
 probability density:

     k
     --  ( n )   j      n-j
     >   (   )  p  (1-p)
     --  ( j )
     j=0

 The terms are not summed directly;  instead the incomplete beta
 integral is employed, according to the formula

     y = bdtr( k, n, p ) = ibeta( n-k, k+1, 1-p ).

 The arguments must be positive, with p ranging from 0 to 1.

 Also see FUNCTIONS and PROBABILITY.
≡expressions functions bdtrc
≡functions bdtrc
≡bdtrc
 ┌──────────────────────────────────────────────────────────────────────┐
 │   bdtrc                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 bdtrc(k,n,p) returns the sum of the terms k+1 through n of the Binomial
 probability density:

     n
     --  ( n )   j      n-j
     >   (   )  p  (1-p)
     --  ( j )
     j=k+1

 The terms are not summed directly;  instead the incomplete beta integral
 is employed, according to the formula

     y = bdtrc( k, n, p ) = ibeta( k+1, n-k, p ).

 The arguments must be positive, with p ranging from 0 to 1.

 Also see FUNCTIONS and PROBABILITY.
≡expressions functions bdtri
≡functions bdtri
≡bdtri
 ┌──────────────────────────────────────────────────────────────────────┐
 │   bdtri                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 bdtri(k,n,y) finds the event probability p such that the sum of the
 terms 0 through k of the Binomial probability density is equal to the
 given cumulative probability y.  This is accomplished using the inverse
 beta integral function and the relation

     1 - p = ibetai( n-k, k+1, y ).

 Also see FUNCTIONS and PROBABILITY.
≡expressions functions nbdtr
≡functions nbdtr
≡nbdtr
 ┌──────────────────────────────────────────────────────────────────────┐
 │   nbdtr                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 nbdtr(k,n,p) returns the sum of the terms 0 through k of the negative
 binomial distribution:

     k
     --  ( n+j-1 )   n      j
     >   (       )  p  (1-p)
     --  (   j   )
     j=0

 In a sequence of Bernoulli trials, this is the probability that k or
 fewer failures precede the nth success.

 The terms are not computed individually;  instead the incomplete beta
 integral is employed, according to the formula

     y = nbdtr( k, n, p ) = ibeta( n, k+1, p ).

 The arguments must be positive, with p ranging from 0 to 1.

 Also see FUNCTIONS and PROBABILITY.
≡expressions functions nbdtrc
≡functions nbdtrc
≡nbdtrc
 ┌──────────────────────────────────────────────────────────────────────┐
 │   nbdtrc                                                             │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 nbdtrc(k,n,p) returns the sum of the terms k+1 to infinity of the negative
 binomial distribution:

     inf
     --  ( n+j-1 )   n      j
     >   (       )  p  (1-p)
     --  (   j   )
     j=k+1

 The terms are not computed individually;  instead the incomplete beta
 integral is employed, according to the formula

     y = nbdtrc( k, n, p ) = ibeta( k+1, n, 1-p ).

 The arguments must be positive, with p ranging from 0 to 1.

 Also see FUNCTIONS and PROBABILITY.
≡expressions functions btdtr
≡functions btdtr
≡btdtr
 ┌──────────────────────────────────────────────────────────────────────┐
 │   btdtr                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 btdtr(a,b,x) returns the area from zero to x under the beta density
 function:
                              x
                -             -
               | (a+b)       | |  a-1      b-1
     P(x)  =  ----------     |   t    (1-t)    dt
               -     -     | |
              | (a) | (b)   -
                             0

 This function is identical to the incomplete beta integral function
 ibeta(a, b, x).

 The complemented function is

     1 - P(1-x) = ibeta( b, a, x )

 Also see FUNCTIONS and PROBABILITY.
≡expressions functions chdtr
≡functions chdtr
≡chdtr
 ┌──────────────────────────────────────────────────────────────────────┐
 │   chdtr                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 chdtr(df,x) returns the area under the left hand tail (from 0 to x) of
 the Chi square probability density function with v degrees of freedom.

                                     inf.
                                       -
                           1          | |  v/2-1  -t/2
     P( x | v )   =   -----------     |   t      e     dt
                       v/2  -       | |
                      2    | (v/2)   -
                                      x

 where x is the Chi-square variable.

 The incomplete gamma integral is used, according to the formula

     y = chdtr( v, x ) = igamma( v/2.0, x/2.0 ).

 The arguments must both be positive.

 Also see FUNCTIONS and PROBABILITY.
≡expressions functions chdtrc
≡functions chdtrc
≡chdtrc
 ┌──────────────────────────────────────────────────────────────────────┐
 │   chdtrc                                                             │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 chdtrc(v,x) returns the area under the right hand tail (from x to
 infinity) of the Chi square probability density function with v
 degrees of freedom:
                                     inf.
                                       -
                           1          | |  v/2-1  -t/2
     P( x | v )   =   -----------     |   t      e     dt
                       v/2  -       | |
                      2    | (v/2)   -
                                      x

 where x is the Chi-square variable.

 The incomplete gamma integral is used, according to the formula

     y = chdtr( v, x ) = igamc( v/2.0, x/2.0 ).

 The arguments must both be positive.

 Also see FUNCTIONS and PROBABILITY.
≡expressions functions chdtri
≡functions chdtri
≡chdtri
 ┌──────────────────────────────────────────────────────────────────────┐
 │   chdtri                                                             │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 chdtri(df,y) finds the Chi-square argument x such that the integral
 from x to infinity of the Chi-square density is equal to the given
 cumulative probability y.

 This is accomplished using the inverse gamma integral function and
 the relation

     x/2 = igami( df/2, y )

 Also see FUNCTIONS and PROBABILITY.
≡expressions functions fdtr
≡functions fdtr
≡fdtr
 ┌──────────────────────────────────────────────────────────────────────┐
 │   fdtr                                                               │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 fdtr(df1,df2,x) returns the area from zero to x under the F density
 function (also known as Snedcor's density or the variance ratio density).
 This is the density of x = (u1/df1)/(u2/df2), where u1 and u2 are random
 variables having Chi square distributions with df1 and df2 degrees of
 freedom, respectively.

 The incomplete beta integral is used, according to the formula

     P(x) = ibeta( df1/2, df2/2, (df1*x/(df2 + df1*x) ).

 The arguments a and b are greater than zero, and x x is nonnegative.

 Also see FUNCTIONS and PROBABILITY.
≡expressions functions fdtrc
≡functions fdtrc
≡fdtrc
 ┌──────────────────────────────────────────────────────────────────────┐
 │   fdtrc                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 fdtrc(df1,df2,x) returns the area from x to infinity under the F density
 function (also known as Snedcor's density or the variance ratio density).

                        inf.
                         -
                1       | |  a-1      b-1
   1-P(x)  =  ------    |   t    (1-t)    dt
              B(a,b)  | |
                       -
                        x

 The incomplete beta integral is used, according to the formula

     P(x) = ibeta( df2/2, df1/2, (df2/(df2 + df1*x) ).

 Also see FUNCTIONS and PROBABILITY.
≡expressions functions fdtri
≡functions fdtri
≡fdtri
 ┌──────────────────────────────────────────────────────────────────────┐
 │   fdtri                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 fdtri(df1,df2,y) returns the F density argument x such that the integral
 from x to infinity of the F density is equal to the given probability y.

   This is accomplished using the inverse beta integral
   function and the relations

        z = ibetai( df2/2, df1/2, y )
        x = df2 (1-z) / (df1 z).

   Note: the following relations hold for the inverse of
   the uncomplemented F distribution:

        z = ibetai( df1/2, df2/2, y )
        x = df2 z / (df1 (1-z)).

 Also see FUNCTIONS and PROBABILITY.
≡expressions functions gdtr
≡functions gdtr
≡gdtr
 ┌──────────────────────────────────────────────────────────────────────┐
 │   gdtr                                                               │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 gdtr(a,b,x) returns the integral from zero to x of the gamma probability
 density function:

                  x
          b       -
         a       | |   b-1  -at
   y =  -----    |    t    e    dt
         -     | |
        | (b)   -
                 0

 The incomplete gamma integral is used, according to the relation

     y = igamma( b, ax ).

 Also see FUNCTIONS and PROBABILITY.
≡expressions functions gdtrc
≡functions gdtrc
≡gdtrc
 ┌──────────────────────────────────────────────────────────────────────┐
 │   gdtrc                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 gdtrc(a,b,x) returns the integral from x to infinity of the gamma
 probability density function:

                 inf.
          b       -
         a       | |   b-1  -at
   y =  -----    |    t    e    dt
         -     | |
        | (b)   -
                 x

 The incomplete gamma integral is used, according to the relation

     y = igamc( b, ax ).

 Also see FUNCTIONS and PROBABILITY.
≡expressions functions ndtr
≡functions ndtr
≡ndtr
 ┌──────────────────────────────────────────────────────────────────────┐
 │   ndtr                                                               │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 ndtr(x) returns the area under the Gaussian probability density
 function, integrated from minus infinity to x:

                              x
                               -
                     1        | |          2
      ndtr(x)  = ---------    |    exp( - t /2 ) dt
                 sqrt(2pi)  | |
                             -
                            -inf.

               =  ( 1 + erf(z) ) / 2
               =  erfc(z) / 2

 where z = x/sqrt(2).  Computation is via the functions erf and erfc.

 Also see FUNCTIONS and PROBABILITY.
≡expressions functions ndtri
≡functions ndtri
≡ndtri
 ┌──────────────────────────────────────────────────────────────────────┐
 │   ndtri                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 ndtri(y) returns the argument, x, for which the area under the Gaussian
 probability density function (integrated from minus infinity to x) is
 equal to y.

 Also see FUNCTIONS and PROBABILITY.
≡expressions functions pdtr
≡functions pdtr
≡pdtr
 ┌──────────────────────────────────────────────────────────────────────┐
 │   pdtr                                                               │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 pdtr(k,m) returns the sum of the first k terms of the Poisson
 distribution:

     k       j
     --   -m  m
     >   e    --
     --     j!
    j=0

 The terms are not summed directly;  instead the incomplete gamma integral
 is employed, according to the relation

     y = pdtr( k, m ) = igamc( k+1, m ).

 The arguments must both be positive.

 Also see FUNCTIONS and PROBABILITY.
≡expressions functions pdtrc
≡functions pdtrc
≡pdtrc
 ┌──────────────────────────────────────────────────────────────────────┐
 │   pdtrc                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 pdtrc(k,m) returns the sum of the terms k+1 to infinity of the Poisson
 distribution:

    inf.       j
     --   -m  m
     >   e    --
     --       j!
    j=k+1

 The terms are not summed directly;  instead the incomplete gamma integral
 is employed, according to the formula

     y = pdtrc( k, m ) = igamma( k+1, m ).

 The arguments must both be positive.

 Also see FUNCTIONS and PROBABILITY.
≡expressions functions pdtri
≡functions pdtri
≡pdtri
 ┌──────────────────────────────────────────────────────────────────────┐
 │   pdtri                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 pdtri(k,y) finds the Poisson variable x such that the integral from
 0 to x of the Poisson density is equal to the given probability y.

 This is accomplished using the inverse gamma integral function and
 the relation m = igami( k+1, y ).

 Also see FUNCTIONS and PROBABILITY.
≡expressions functions stdtr
≡functions stdtr
≡stdtr
 ┌──────────────────────────────────────────────────────────────────────┐
 │   stdtr                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 stdtr(k,t) computes the integral from minus infinity to t of the Student
 t distribution with integer k > 0 degrees of freedom:

                                        t
                                        -
                                       | |
                -                      |         2   -(k+1)/2
               | ( (k+1)/2 )           |  (     x   )
         ----------------------        |  ( 1 + --- )        dx
                       -               |  (      k  )
         sqrt( k pi ) | ( k/2 )        |
                                     | |
                                      -
                                     -inf.

 Relation to incomplete beta integral:

     1 - stdtr(k,t) = 0.5 * ibeta( k/2, 1/2, z )
 where
     z = k/(k + t**2).

 Also see FUNCTIONS and PROBABILITY.
≡bessel
 ┌──────────────────────────────────────────────────────────────────────┐
 │   Bessel Functions                                                   │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 Bessel functions arise in solving differential equations for systems
 with cylindrical symmetry.

 Jn(x) is often called the Bessel function of the first kind, or simply
 the Bessel function.  Yn(x) is referred to as the Bessel function of
 the second kind, the Weber function, or the Newmann function.  In(x)
 and Kn(x) are modified Bessel functions.  They are equivalent to the
 usual Bessel functions Jn and Yn evaluated for purely imaginary
 arguments.

 Twelve Bessel functions are provided with Graphica: besi0, besi1,
 besin, besj0, besj1, besjn, besk0, besk1, beskn, besy0, besy1 and besyn.

 For example, besi0(x) returns the modified Bessel function I0 of x,
 besj1(x) returns the Bessel function J1 of x, and besyn(n,x) returns
 the Bessel function Y of general integer order n (n>1).

 All Bessel functions expect x to be in radians.

 Also see BESI0, BESI1, BESIN, BESJ0, BESJ1, BESJN, BESK0, BESK1, BESKN,
 BESY0, BESY1, and BESYN for more details.
≡expressions functions besi0
≡functions besi0
≡besi0
 ┌──────────────────────────────────────────────────────────────────────┐
 │   besi0                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 besi0(x) returns the i0th (modified) Bessel function of x, where x
 is in radians.

 Also see BESSEL and FUNCTIONS.
≡expressions functions besi1
≡functions besi1
≡besi1
 ┌──────────────────────────────────────────────────────────────────────┐
 │   besi1                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 besi1(x) returns the i1st (modified) Bessel function of x, where x
 is in radians.

 Also see BESSEL and FUNCTIONS.
≡expressions functions besin
≡functions besin
≡besin
 ┌──────────────────────────────────────────────────────────────────────┐
 │   besin                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 besin(n,x) returns the inth (modified) Bessel function of x, where x
 is in radians and n > 1.

 Also see BESSEL and FUNCTIONS.
≡expressions functions besj0
≡functions besj0
≡besj0
 ┌──────────────────────────────────────────────────────────────────────┐
 │   besj0                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 besj0(x) returns the j0th Bessel function of x, where x is in radians.

 Also see BESSEL and FUNCTIONS.
≡expressions functions besj1
≡functions besj1
≡besj1
 ┌──────────────────────────────────────────────────────────────────────┐
 │   besj1                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 besj1(x) returns the j1st Bessel function of x, where x is in radians.

 Also see BESSEL and FUNCTIONS.
≡expressions functions besjn
≡functions besjn
≡besjn
 ┌──────────────────────────────────────────────────────────────────────┐
 │   besjn                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 besjn(n,x) returns the jnth Bessel function of x, where x is in
 radians and n > 1.

 Also see BESSEL and FUNCTIONS.
≡expressions functions besk0
≡functions besk0
≡besk0
 ┌──────────────────────────────────────────────────────────────────────┐
 │   besk0                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 besk0(x) returns the k0th (modified) Bessel function of x, where x
 is in radians.

 Also see BESSEL and FUNCTIONS.
≡expressions functions besk1
≡functions besk1
≡besk1
 ┌──────────────────────────────────────────────────────────────────────┐
 │   besk1                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 besk1(x) returns the k1st (modified) Bessel function of x, where x
 is in radians.

 Also see BESSEL and FUNCTIONS.
≡expressions functions beskn
≡functions beskn
≡beskn
 ┌──────────────────────────────────────────────────────────────────────┐
 │   beskn                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 beskn(n,x) returns the knth (modified) Bessel function of x, where x
 is in radians and n > 1.

 Also see BESSEL and FUNCTIONS.
≡expressions functions besy0
≡functions besy0
≡besy0
 ┌──────────────────────────────────────────────────────────────────────┐
 │   besy0                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 besy0(x) returns the y0th Bessel function of x, where x is in radians.

 Also see BESSEL and FUNCTIONS.
≡expressions functions besy1
≡functions besy1
≡besy1
 ┌──────────────────────────────────────────────────────────────────────┐
 │   besy1                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 besy1(x) returns the y1st Bessel function of x, where x is in radians.

 Also see BESSEL and FUNCTIONS.
≡expressions functions besyn
≡functions besyn
≡besyn
 ┌──────────────────────────────────────────────────────────────────────┐
 │   besyn                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 besyn(n,x) returns the ynth (modified) Bessel function of x, where x
 is in radians and n > 1.

 Also see BESSEL and FUNCTIONS.
≡environment
 ┌──────────────────────────────────────────────────────────────────────┐
 │   Environment Variables                                              │
 └──────────────────────────────────────────────────────────────────────┘

 An environment variable is used to specify from the operating system
 certain parameters of program operation.  The "environment" is really
 just a common area of memory that programs can write to and read from.
 Some programs are geared to look specifically at the environment to find
 particular data important to their operation.  They may ask you to place
 a variable into the environment equal to a certain value so that they
 can find support files which could not be found otherwise.

 A number of shell environment variables are understood by Graphica.
 None of these are required, but may be useful:

     - GRAPTERM
     - GRAPDUMP
     - GRAPHELP
     - GRAPHINI
     - GRAPFONT

 GRAPTERM may be used as the name of the terminal type to be used.  This
 overrides any terminal type sensed by Graphica on start up, but is itself
 overridden by the 'graphica.ini' or other start-up file, and of course by
 later explicit changes.

 GRAPDUMP is used as the default terminal type used when dumping graphics
 to a file.

 GRAPHELP may be defined to be the pathname of the help file.  If this
 environment variable is not defined, Graphica will try to look for the
 help file somewhere in your DOS path.  If the help file can't be found,
 you have no on-line help available.

 GRAPHINI may be used as the pathname of a startup-up file.  The default
 name is 'graphica.ini' on DOS/VAX systems and '.graphica' on UNIX.  The
 DOS version of Graphica will use the entire search path to look for it.

 GRAPFONT specifies where Graphica's font files are located.  If the
 font files are not somewhere in your DOS path, you may specify an
 environment variable called GRAPFONT containing the font directory.
 For example, if the fonts are in C:\GRAPHICA\FONTS, then you would
 specify,

     SET GRAPFONT=C:\GRAPHICA\FONTS

 somewhere in your autoexec.bat file or in a batch file just before
 running Graphica.  Graphica will then find the necessary font file
 in that directory and load it at runtime.

 DOS Environment Variables
 -------------------------

 If we were to look at the DOS environment (by typing the SET command
 at the DOS prompt), we might see a listing similar to the one below:

     COMSPEC=C:\COMMAND.COM
     PATH=C:\;C:\DOS;C:\UTIL

 Other values might be present, like PROMPT=$P$G, and more depending
 on the types and kinds of software you are running.

 Environment variables are specified before running Graphica.  They
 can be specified directly from DOS, from within the AUTOEXEC.BAT file,
 or from within any batch file.

 The command for setting an environment variable is:

     SET PARAMETER=PARAMETER VALUE

 Examples:

     C:\SET GRAPDUMP=hpgl                   (sets the dump terminal type)
     C:\SET GRAPHELP=c:\plot\graphica.hlp                 (the help file)
     C:\SET GRAPHINI=c:\plot\graphica.ini             (the start-up file)
     C:\SET GRAPFONT=C:\GRAPHICA\FONT                        (font files)

 In general, you won't have to set the DOS environment variable GRAPTERM if
 you have any of the commonly available graphics monitors, CGA/EGA/VGA, etc.

 VAX/VMS Logical Symbols
 -----------------------

 On a VAX, environment variables are called 'symbols.'  The format for
 defining a symbolic name for a character string is:

              symbol-name :== expression

 For example, we could define the following symbols:

     $ LIST :== "DIRECTORY"
     $ TIME :== "SHOW TIME"
     $ QP :== "SHOW QUEUE/DEVICE"
     $ SS :== "SHOW SYMBOL"

 To look at the environment, you may type SHOW SYMBOL/GLOBAL/ALL at the
 $ prompt).

 Examples:

     $ GRAPDUMP :== hpgl                       (sets the dump terminal type)
     $ GRAPTERM :== raster                          (sets the terminal type)
     $ GRAPHINI :== dua7:[user.junk]graph.ini            (the start-up file)

 (GRAPHELP should already have been defined for you.)

 Unix Shell Variables
 --------------------

 In a UNIX environment, things get a little bit confusing because of the
 different shells that you might be running.  Environment variables can
 be shown by using the 'printenv' command (Korn-shell or /bin/sh), the
 'setenv' command (c-shell or /bin/csh) or the 'AEGIS' command (Aegis
 shell on Apollos).  To set them, do

     $ GRAPTERM=apollo
     $ GRAPDUMP=postscript
     $ export GRAPDUMP
     $ export GRAPTERM

 Also see STARTUP.
≡startup
 ┌──────────────────────────────────────────────────────────────────────┐
 │   Startup File                                                       │
 └──────────────────────────────────────────────────────────────────────┘

 When Graphica is run, it looks for an initialization file to load.
 This file is called 'graphica.ini'.  If this file is not found in the
 current directory (or entire search path on DOS systems), the program
 will look for a start-up file pointed to by the environment variable
 GRAPHINI.

 If the initialization file is found, Graphica executes the commands
 in that file.  This is most useful for setting your terminal type and
 defining any functions or variables which you use often.

 Also see ENVIRONMENT.
≡text
 ┌──────────────────────────────────────────────────────────────────────┐
 │   Text Primitives                                                    │
 └──────────────────────────────────────────────────────────────────────┘

 Text primitives generate a string of characters on a display device
 in a specific location in the world coordinate system.  The character
 string may comprise letters, numerals, and symbols.  Text primitives
 provide a method for labeling and clarifying a graphical image.

 This section describes the control sequences which are accessible
 when specifying a string label.  The control sequences are only available
 when using a software generated font.  Graphica recognizes \ as a special
 character used to signal the start of an escape sequence.  There are two
 kinds of escape sequences, those that take an argument and those that do
 not.

 The two escape sequences that do not take an argument are:

     \U     move up half a character size
     \D     move down half a character size

 The following take one integer argument immediately after the escape
 sequence and a space after it to delineate the end (the space is not
 printed):

     \Cn    set color to n
     \C-1   reset color to the default
     \Fn    set font to n
     \F-1   reset font to the default
     \Sn    set character size to n % of the default size
     \S-1   reset character size to the default size
     \Ln    set character slant to n degrees
     \L-1   reset character slant to the default slant
     \An    print ascii n
     \rn    save current position in register n
     \Rn    restore position from register n

 Examples:

 to print greek characters such as in 'beta = x + lambda':
     » label '\F2 b\F1 = x + \F2 l'

 to label the x-axis with 'velocity U sub f':
     » xlabel 'velocity, U\Dsub'

 to place a top label of 'stress in dynes per cm squared':
     » top label 'stress (dyn\cm\U2\D)'

 to get 'x squared plus y squared':
     » label 'x\U2\D + y\U2'

 and finally, an advanced example.  To get 'A sub b sup beta':
     » label 'A\r1 \Db\R1 \U\F2 b'

 This last example is translated as: do A, save this spot, go down half,
 do b, restore the saved spot, go up half, switch to font 2 (greek simplex),
 do beta.  Notice the use of registers to stack characters on top of each
 other.

 To get a backslash, simply use one \.
≡version
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   version                                                            │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 The 'version' command displays:

     - your Graphica version number
     - pertinent copyright and other information

 Also on DOS systems:

     - the amount of system RAM available
     - the amount of disk space available in the current drive
≡what
 Syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   what                                                               │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 'what' shows a directory listing of the .plt files on the disk in the
 current directory.  Files with other extensions are not shown.

 Also see DEL, DIR, SHELL and TYPE.
≡variables
≡userdefined
≡who
 User-defined function syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   <function-name>( <dummyvar 1> {, <dummyvar 2> } ) = <expression>   │
 │                                                                      │
 │   where                                                              │
 │   <expression> is defined in terms of <dummyvar 1> and <dummyvar 2>  │
 └──────────────────────────────────────────────────────────────────────┘

 User-defined variable syntax:
 ┌──────────────────────────────────────────────────────────────────────┐
 │   <variable-name> = <constant-expression>                            │
 │   variables                                                          │
 └──────────────────────────────────────────────────────────────────────┘

 Description:

 You may define your own functions and variables.  User-defined functions
 and variables may be used anywhere an expression is called for.  A function
 refers to a general expression and can take one or two arguments (dummy
 variables).

 The WHO or VARIABLES command lists all pre-defined and user-defined
 variables together with their values.

 The following variables have already been defined for you:

     pi      = 3.14159
     e       = 2.71828
     catalan = 0.91597
     degree  = 0.01745
     ufactor = 1.00000
     gamma   = 0.57721
     golden  = 1.61803

 where pi is the mathematical constant π, e is the exponential constant,
 catalan is Catalan's constant, degree gives the number of radians in one
 degree (pi/180), ufactor is a conversion factor used to convert from
 inches to user-defined units (cm and mm), gamma is Euler's constant,
 and golden is the golden ratio (1+sqrt(5))/2.  These constants have
 been predefined for you but you may change them (so they are really
 variables).

 Examples:

     » w = 2
     » q = floor(tan(pi/2 - 0.1))
     » f(x) = sin(w*x)
     » sinc(x) = sin(pi*x)/(pi*x)
     » delta(t) = (t == 0)
     » ramp(t) = (t > 0) ? t : 0
     » comb(n,k) = n!/(k!*(n-k)!)

 Note:  case matters, e.g., 'Alpha' is different from 'alpha'.
 Also see FUNCTIONS.
≡nodisplay
 ┌──────────────────────────────────────────────────────────────────────┐
 │   nodisplay                                                          │
 └──────────────────────────────────────────────────────────────────────┘

 This command shuts off the display of the mouse position on DOS systems
 at the bottom right corner of the screen in graphics mode.
≡tips
 ┌──────────────────────────────────────────────────────────────────────┐
 │   Tips                                                               │
 └──────────────────────────────────────────────────────────────────────┘

 Here some tips to help you get started with Graphica:

 - Pressing any key while the introductory screen is shown will turn
   it off and take you directly to the command line.

 - Use the arrow keys (up, down, right, left ) to recall previous
   commands or edit the current command line.

 - Type 'what' to get a list of all the *.plt script files you may
   have in the current directory.

 - You may put more than one command on a line--just separate each
   command by a semicolon, for example,

     » plot x y add ; column 3 is y ; plot x y connect

 - Pressing F1 calls up the help system.  Pressing F10 displays the
   graph on the screen.
≡errors
 ┌──────────────────────────────────────────────────────────────────────┐
 │   Errors                                                             │
 └──────────────────────────────────────────────────────────────────────┘

 When Graphica encounters an error caused by an incorrect command in a
 script file or on the command line it will issue an error message.  If
 the bad command was in a script file, the line number will be given.

 You can type SHOW at the command line to see everything you've plotted
 so far.  You can also correct errors in a script file by "shelling" out
 to the OS or issue a $edit command (to invoke the editor from within
 Graphica for example) where 'edit' is the name of your favorite editor.
≡bugs
 ┌──────────────────────────────────────────────────────────────────────┐
 │   Notes                                                              │
 └──────────────────────────────────────────────────────────────────────┘

 No text control characters (see HELP TEXT) when using the hardware font.

 Subscript/superscript size hasn't been implemented yet.  Use the \S
 command (described in TEXT) to change the character size of superscripts
 and subscripts.

 ┌──────────────────────────────────────────────────────────────────────┐
 │   Bug Reports                                                        │
 └──────────────────────────────────────────────────────────────────────┘

 Graphica is under constant revision, updating and being given expanded
 capabilities.  Prior to each release, the developer strives to verify new
 features and bug fixes through testing.  However, as inevitably happens
 with any software, some bugs do survive and show up in user runs.  Users
 can aid in the problem fixing process by following the guidelines below:

 a) Report any unusual messages, computed results, format overflows,
 etc.  even though the program appears to have terminated normally.

 b) For any abnormal program termination, save the input file and all
 output obtained by running the program.

 Reported problems will be fixed as quickly as possible.  In most
 instances, alternate methods or techniques of plot formulation and
 input are available to permit graphing despite the bug.  All problems
 encountered with Graphica should be reported to:

 ┌──────────────────────────────────────────────────────────────────────┐
 │   Antonio Montes      Internet address : [e-mail]  │
 │   Postbus 13          CompuServe userid: 71031,1162                  │
 │   2350 AA Leiderdorp                                                 │
 │   The Netherlands                                                    │
 └──────────────────────────────────────────────────────────────────────┘