PC World Komputer 1996 February/PCWK0296.iso/sharewar/os2/grafika/splot/os2splot.hlp

Text File | 1994-10-06 | 45.2 KB | 1,374 lines

<general>
    To plot a figure load a .spt file.
 For example:

 <esc> edit demo\logaxes.spt or use the 'Open'
 button in the 'File' menu.

 then hit CTRL G or 'Exec' button.

    The next section explains how to use the mouse. For
 help with the editor select help in the editor window.

 Using The Mouse

    Double clicking the left mouse button with the mouse on
 the drawing page inserts the current x,y coordinates into
 the text file at the current text cursor location. If the
 mouse cursor is in the text region then hitting the left
 mouse button will move the current text cursor to the mouse
 cursor location. The left mouse button is also used to
 select items in drop down menus. A rubber band box is drawn
 by pressing the left mouse button with the mouse over the
 plot window and dragging the mouse with the left button held
 down. The second point of the box is set to the location at
 which the button is released. Double clicking the left mouse
 button in the text window results in an action depending on
 the type of file and type of word under the mouse cursor.
 If the word under the cursor is a variable the value of the
 variable or constant is displayed. If the word is a
 function then the help screen for that function will be
 loaded. If the current file has a read only attribute then
 the editor attempts to interpret the word under the cursor
 as a file name and subsequently load in that file.

    The right mouse button is used for highlighting
 elements of a drawing. If the mouse cursor is on top of a
 displayed element on the drawing page and the right mouse
 button is hit then the corresponding element is highlighted
 in intense white and the text cursor jumps to the
 corresponding line in the text that generated that element.
 Conversely, if the mouse cursor is on the text side hitting
 the right mouse button will highlight any graphics elements
 generated by the line under the mouse cursor. This feature
 is very useful for finding the code associated with a
 particular element of a drawing or the reverse. Clicking the
 right mouse button on a drop down menu item will open a
 help window for that item if available.

    When the mouse cursor is on the drawing page the
 current coordinates are printed at the bottom. The units
 and origin used are those in effect at the end of the last
 program execution. The default units are cm with the origin
 in the bottom left corner of the page. Pressing the middle
 mouse button (or both the left and right mouse buttons
 together on two button mice) with the mouse pointer on the
 drawing page causes the current coordinate reference point
 to be reset so that the current coordinate line
 subsequently reports the distance from this point.


    Actions associated with the menu buttons

    There are several menu buttons along the top of the
 display. The action of these buttons is as follows.
 Starting at the left top there are four buttons labelled
 'Draw', 'Slib', 'Cnst', 'SetO' and 'Keyw'. These activate
 drop down menus which allow a function to be selected and
 inserted into the text. The 'Draw' functions are a suite of
 drawing routines which cause lines, arcs, text etc. to be
 drawn to the page. The 'SetO' menu is a list of textual
 names for numerical constants which are used in conjunction
 with the set(); command to change attributes of the current
 graphics state such as the current colour, line width, line
 style, axes type, etc. Choosing set from the list of
 drawing functions automatically opens a menu with only an
 appropriate subset of these and is the recommended
 approach. The 'Slib' button allows selection of a standard
 C library function. Most of these are math functions such
 as sin() and will not be required for making ordinary
 plots. They are however useful for manipulating data before
 plotting or generating data mathematically all from within
 Splot. The 'Cnst' button opens a menu containing all the
 constants defined in splot.h. The last button of this group
 'KeyW' opens a list of C keywords for selection. The only
 one of these that is of interest for ordinary plots is
 'main'. Every file that generates a plot or drawing must
 start with

#include splot.h
main
   {
   /* list of drawing commands go here */
   /*   between the braces on as many*/
   /* lines as necessary */
   }

    This is all automatically inserted in the text by
 selecting 'main'. The remaining keywords in this list are
 only of interest when constructing loops or branches.

    The next button labelled 'Misc' opens a sub menu
 containing the options 'Reset', 'Redraw' , 'Coord Match'
 and 'Relative Coord'. 'Reset' resets splot to its initial
 state and erases the current drawing. The 'Redraw' button
 can be useful if Splot is in the incremental draw mode in
 order to fix up blemishes caused by out of order drawing ad
 erasing. 'Redraw' just re draws the current plot. The button
 'Coord Match' toggles the current units from cm to units
 matching those defined in the last axes_box() and back. The
 button 'Relative Coord' toggles the coordinate display from
 reporting the absolute coordinate to reporting the distance
 between the mouse position and the current point defined
 using the middle mouse button or double clicking the left
 mouse button over the plot window.

    The next button along the top is concerned with
 displaying the drawing. The default size of the drawing is
 one which fits on a standard 8 x 11 inch piece of paper if
 printed. However, as the screen resolution is not as good
 as that of printers it is possible to zoom in on part of a
 drawing in order to get a better view. To zoom in on part
 of a drawing hold down the left button and drag the mouse
 to enclose the region of interest. Then select the zoom
 button and pick the drop down menu item 'Box Zoom'. The
 button 'Undo Zoom' restores the previous view. The buttons
 'Save View' and 'Rest View' allow interesting views to be
 saved on a stack and restored respectively.

<product_info>
 This is Splot version 1.2.0

 THIS PROGRAM WAS WRITTEN BY THOMAS W. STEINER
 COPYRIGHT 1992 - 1994, ALL RIGHTS RESERVED
 THERE IS NO WARRANTY OF ANY KIND. USE AT YOUR OWN RISK.
 THIS IS NOT FREEWARE. TO REGISTER YOUR COPY SEND $50 TO

       T.W. Steiner
    312 - 1230 Haro St.
     Vancouver, BC, V6E - 4J9
          Canada
       e-mail [e-mail]

 Registered users will receive upgrades
 as they become available

<abs>
 int abs(int i);

 Returns the absolute value of i;

<acos>
 double acos(double x);

 Returns the arc cosine of the value x. x must be
 between -1 and 1. Returns a value between 0 and pi.

<asin>
 double asin(double x);

 Returns the arc sine of the value x. x must be between
 -1 and 1. Returns a value between -pi/2 and pi/2.

<atan>
 double atan(double x);

 Returns the arc tangent of the value x. Returns a value
 between -pi/2 and pi/2.

<atan2>
 double atan2(double y,double x);

 Returns the arc tangent of the value y/x. Returns a value
 between -pi and pi.

<atoi>
 int atoi(char *str);

 Converts a string to an integer. The string must contain
 only digits.

<atof>
 double atof(char *str);

 Converts a string to a double. The string must contain only
 digits and 'e', 'E', '.', '-' and '+' .

<ceil>
 double ceil(double x);

 Rounds up x to nearest integer value.

<cos>
 double cos(double x);

 Returns the cosine of x. x is specified in degrees.

<exit>
 void exit(int status);

 Terminates the execution of the program. If the status is 0
 then it will be considered a normal exit otherwise an error
 induced exit.

<exp>
 double exp(double x);

 Calculates the exponential function e^x.

<fabs>
 double fabs(double x);

 Returns the absolute value of x. It is like abs() but works
 with floating point numbers rather than integers.

<floor>
 double floor(double x);

 Rounds down x to the nearest integer.

<fmod>
 double fmod(double x,double y);

 Returns the remainder of x/y.

<free>
 void free(char *ptr);

 Frees the block of memory pointed to by ptr. The memory
 must have been previously allocated using malloc().

<log>
 double log(double x);

 Returns the natural log of x.

<log10>
 double log10(double x);

 Returns the log base 10 of x.

<malloc>
 char *malloc(int size);

 Allocates a block of memory of size bytes and returns a
 pointer to the block. malloc returns NULL if there is
 insufficient free memory.

<pow>
 double pow(double x,double y);

 Calculates x to the power y.

<puts>
 int puts(char *str);

 This routine writes the string str to the output file and
 starts a new line.

<printf>
 int printf(char *format,...);

 Prints the formatted data to the output file. The format
 string specifies the type and number of values to print.
 Some common examples include:

 printf("i = %d",i); prints the
 integer value i.

 printf("x = %g",x); prints the
 floating point value x.

 printf("text = %s",str); prints the
 string str.

 Multiple values can be printed as in
 printf("%d %d %g %s",i,j,x,str);

 The format specifiers can also include field width
 information and justification etc. Consult a standard C
 text for more details.

<print>
 void print(v,...);

 Prints the value v which can be of any scalar type. i.e
 int, char, float, double or a pointer. This is not a
 function found in the standard C library.

<sin>
 double sin(double x);

 Returns the sine of x. x must be specified in degrees.

<sqrt>
 double sqrt(double x);

 Calculates the square root of x. x must be a positive
 number.

<sizeof>
 int sizeof(t);

 Returns the number of bytes required to store the value of
 type t.

<sprintf>
 int sprintf(char str,char
     *format,...);

 Prints the formatted data to the string str. The format
 string specifies the type and number of values to print.
 Some common examples include:

 printf("i = %d",i); prints the
 integer value i.

 printf("x = %g",x); prints the
 floating point value x.

 printf("text = %s",str); prints the
 string str.

 Multiple values can be printed as in
 printf("%d %d %g %s",i,j,x,str);

 The format specifiers can also include field width
 information and justification etc. Consult a standard C
 text for more details.

<strcat>
 void strcat(char *dest, char
      *source);

 Concatenates the string source to the string dest.

<strcpy>
 void strcpy(char *dest, char
      *source);

 Copies the string source to the string dest.

<strlen>
 int strlen(char *str);

 Returns the length of the string str.

<tan>
 double tan(double x);

 Calculates the value of the tangent of x. x should be
 specified in degrees.

<abox>
 void abox(double xsi, double
       ysi, double xorig,
       double yorig);

 Adds an axes box to the current path. The box is drawn with
 a size of xsi by ysi and centered on the page. No internal
 coordinate system is set up. Use ascale() for this or use
 axes_box() to combine both functions. The last two
 parameters are optional and if present, specify the position
 of the axes origin relative to the page origin. For the
 last two parameters the special constants XCENTER and
 YCENTER can be used for the x or y position coordinate
 respectively and will cause the axes box to be centered on
 the page along that axis. Using both XCENTER and YCENTER is
 equivalent to the default behaviour with the last two
 parameters absent. abox() is implicitly stroked.

<alineto>
 void alineto(double len, double
     ang);

 Adds a line of length len at an angle of ang with respect
 to the previous line to the current path. Generates an
 error if there is no previous line in the current path.

<arc>
 void arc(double xcen, double ycen, double rad, double
       alpha, double beta);

 Adds a circular arc of radius rad centered at (xcen, ycen)
 to the current path. The starting angle is alpha and the
 stopping angle is beta. The arc is drawn in the counter
 clockwise direction. A straight line section will be added
 from the previous current point if any to the starting
 point of the arc.

<arcn>
 void arcn(double xcen, double ycen, double rad, double
       alpha, double beta);

 Adds a circular arc of radius rad centered at (xcen, ycen)
 to the current path. The starting angle is alpha and the
 stopping angle is beta. The arc is drawn in the clockwise
 direction. A straight line section will be added from the
 previous current point if any to the starting point of the
 arc. Exactly as arc() but draws the arc in the opposite
 direction.

<arcto>
 void arcto(double x1, double y1, double x2, double y2,
        double rad);

 Adds a circular arc of radius rad to the current path. The
 center and angles are chosen so that the arc is tangent to
 the line formed by (x1,y1) and the current point at its
 start and tangent to the line (x1,y1) - (x2,y2) at its end
 point. A straight line segment is added from the current
 point to the start of the arc. An error is generated is
 there is no current point.

<arrowto>
 void arrowto(double x,double y,...);

 Adds a line segment to the current path from the current
 point to (x,y). The line is terminated by drawing an arrow
 head oriented in the direction of the line. More than one
 coordinate point can be specified in the command in which
 case a series of line segments terminated by arrows
 connecting the points will be added to the current path. If
 there is no current point then an error will be generated.
 The size of the arrow head may be changed with the
 set(FONTWIDTH,...); command.

<ascale>
 void ascale(int axes, double xstart, double ystart, double
      xend, double yend);

  or

 void ascale(int axes, double *data, int col,...);

 An internal coordinate system is set up for subsequent
 plotting of data within the existing axes box. The x axis
 start and stop values are xstart and xend respectively and
 ystart, yend for the y axis. for the y axis. If the axis
 choice is XAXES or YAXES rather than XYAXES then only two
 numbers follow the axes specifier rather than four. This
 allows the x and y axes scales to be set independently of
 each other. The alternate format allows for auto scaling to
 the specified data. There can be more than one data array
 in the list in which case the scales are chosen so that
 they will all fit. Each data array can optionally be
 followed by one or two integers specifying which columns to
 use for the x and y values. If axes is not XYAXES only one
 integer is allowed.

<axes_box>
 void axes_box(double xsi, double ysi, double xstart, double
       ystart, double xend, double yend,double xorig, double
       yorig);

 Adds an axes box to the current path. The box is drawn with
 a size of xsi by ysi and centered on the page. An internal
 coordinate system is set up for subsequent plotting of data
 within the box. The x axis start and stop values are xstart
 and xend respectively and ystart, yend for the y axis. for
 the y axis. The last two parameters are optional and if
 present specify the position of the axes origin relative to
 the page origin. For the last two parameters the special
 constants XCENTER and YCENTER can be used for the x or y
 position coordinate respectively and will cause the axes
 box to be centered on the page along that axis. Using both
 XCENTER and YCENTER is equivalent to the default behaviour
 with the last two parameters absent. More flexibility is
 provided by the pair of functions abox() and ascale() which
 provide the functionality of axes_box() in several steps.
 axes_box() is implicitly stroked.

<box>
 void box(double x1, double y1, double x2, double y2);

 Adds a box to the current path. The two end points of the
 box are (x1,y1) and (x2,y2);

<clear>
 void clear();

 Clears the screen when the program is executed.
 This function should not be needed for ordinary plots.

<clip>
 void clip()

 Converts the currently defined path into a clipping path.
 All subsequent drawing operations are then clipped against
 this path and only portions of the drawing on the inside of
 the clip path are displayed. What is inside and what is
 outside depends on whether even-odd or non-zero wind has
 been selected as the fill rule using a set(); If the
 current path is not closed then the current path is first
 closed. If there is no current path an error is generated.
 Clip() is implicitly stroked and takes effect immediately.

<closepath>
 void closepath();

 Closes the current path. A straight line segment is added
 from the current point to the start of the current path as
 set by the moveto() of rmoveto() command at the beginning
 of the path definition. Generates an error if there is no
 current point.

<cmatch>
 void cmatch(int on);

 If the passed parameter is TRUE then it does the necessary
 translations and scaling so that the coordinate system for
 the page matches that used within the axes_box. An error is
 generated if there is no current axes_box. The font scale
 is compensated automatically for the change in coordinate
 system so that characters will still be the same size as
 before. If the parameter is FALSE then the previous
 unmatched coordinates will be restored. If there is no
 parameter TRUE is assumed.

<curveto>
 void curveto(double x1, double y1, double x2, double y2,
          double x3, double y3);

 Adds a Bezier curve section to the current path starting
 at the current point. The curve starts tangent to
 (xcur,ycur) - (x1,x2) and ends tangential to (x2,y2) -
 (x3,y3) at (x3,y3); An error is generated if there is no
 current point.

<drawdata>
 void drawdata(double *data, int xcol, int ycol);

 Draws the data contained in the array data in the current
 axes_box. The numbers xcol and ycol are the columns of the
 array data that are to be used for the x-axis and y-axis
 data respectively. Each row of the array data represents
 one coordinate point to be plotted. The values will be
 plotted using the internal coordinate system established by
 the the call to axes_box. If there is no current axes box
 an error will be generated. The xcol and ycol params are
 optional. If no values are given then xcol = 0 and ycol = 1
 are assumed. drawdata() is implicitly stroked.

<errorbars>
 void errorbars(int axes,double *data, int xcol, int ycol,
        int errcol);

 Draws error bars for the data points in the array "data".
 The first parameter is either XVALS or YVALS indicating
 along which axes the error bars are to be drawn. The
 numbers xcol and ycol are the columns of the array data
 that are to be used for the x-axis and y-axis data
 respectively. Each row of the array data represents one
 coordinate point to be plotted. The values will be plotted
 using the internal coordinate system established by the the
 call to axes_box. The last parameter "errcol" is the column
 of the array "data" which holds the size of the error for
 the corresponding data point in the same row. If there is
 no current axes box an error will be generated.
 errorbars() is implicitly stroked.

<fill>
 void fill();

 Closes the current path if not already closed and fills the
 interior region with the current colour as specified by the
 last set() call. What is inside and what is outside the
 path depends on the currently chosen fill rule. The fill
 rule is either even-odd or non-zero wind (the default) and
 is specified using a set() call. An error is generated if
 there is no current path.

<fitline>
 void fitline(double *data, int xcol,
  int ycol,double *yint,double *slope);

 Fits the best straight line to the data in the array "data"
 using the column xcol of the array as the x values and the
 column ycol as the corresponding y values. The best line is
 drawn constrained to the current axes box. If there is no
 current axes box an error is generated. The last two
 parameters are the returned values giving the y intercept
 and slope of the fitted line. Note that they are pointers
 to doubles which must be declared at the top of the
 program. Given a declaration of the form:

     double slope,yint;

 Call fitline using:

     fitline(data,0,1,&yint,&slope);

 Assuming that the first and second column of data are the x
 and y values respectively. Data points can be excluded from
 the fit by using the set(XRANGE,xmin,xmax); or
 set(YRANGE,ymin,ymax); commands. Only data points within
 the limits will be used for the fit. fitline() is
 implicitly stroked.

<get>
 int or double get(int option, char *str);

 Returns the value of the specified option in the current
 graphics state. The numerical value for single valued
 elements is returned by the function otherwise the return
 value is 0. A text representation of the value is optionally
 returned in str. If used, be sure to allocate a character
 array with sufficient space for str before calling this
 function as in char str[80]; at the top of the program. The
 valid option values are defined in splot.h. See also set()
 for a description of the various options. The returned
 string can be printed using the command puts(str); in the
 program where "str" is the name of the array in the call to
 get(). Returned numerical values can be printed using
 print(value); The second array parameter is optional and is
 only really needed for getting options that are more than
 just a single value such as line patterns.

<grestore>
 void grestore();

 Pops a graphics state off the state stack thereby restoring
 the graphics state that was in effect at the time the
 matching gsave() was executed. In particular, the path, the
 clip path, the line styles, line colours etc. are restored
 to their previous values.

<gsave>
 void gsave();

 Pushes the current graphics state onto the state stack. The
 current path, clip path, line style, colour etc. are saved
 so that they can be restored later using a grestore()
 command.

<label>
 void label(int axis, char *label);

 Add labels to the axes box previously defined. The first
 parameter is which axis to label either BOTTOM, TOP, LEFT
 or RIGHT. The following parameter is the label to be
 printed. The label will be printed centered between the
 appropriate edges of the current axes box. An error is
 generated if there is no current axes box. All labels
 should be after plotdata() if used otherwise spacing from
 the axes may not be correct. The spacing can also be
 changed using set(LABELMARG,...);. label() is implicitly
 stroked.



<lineto>
 void lineto(double x,double y,...);

 Adds a line segment to the current path from the current
 point to (x,y). More than one coordinate point can be
 specified in the command in which case a series of line
 segments connecting the points will be added to the current
 path. If there is no current point then an error will be
 generated.

<moveto>
 void moveto(double x, double y);

 Sets the current point to (x,y). Also sets the path close
 point to (x,y) for subsequent use with closepath(). Many
 path building commands such as curveto() and lineto() require
 that a current point exist before calling them.

<newpath>
 void newpath();

 Resets the current path to NULL and also causes the current
 point to be undefined. Furthermore, it turns off the
 implicit stroking of elements that are normally implicitly
 stroked such as text();. Thus using newpath(); these
 elements can be added to a path which must then be
 explicitly stroked. stroke() turns on implicit stroking
 again.

<plotdata>
 void plotdata(double *data, int xcol, int ycol);

 Plots the data found in array data in a box. This command
 chooses the scale sizes tick marks etc. to display the data
 which is assumed to be in order of monotonically increasing
 or decreasing x value order. The parameters xcol and ycol
 specify which columns of the array data to use for the x
 and y values respectively. The xcol and ycol params are
 optional. If no values are given then xcol = 0 and ycol = 1
 are assumed. If the default choices of plotdata are not
 acceptable a plot can be generated using the step by step
 method using axes_box(), tickmarks(), ticklabels() and
 drawdata(). The data must first be read in to array data
 using readdata(). plotdata() is implicitly stroked.

<rarrowto>
 void rarrowto(double x, double y,...);

 Adds a line segment to the current path from the current
 point to the current point plus x, y. The line is
 terminated by drawing an arrow head oriented in the
 direction of the line. This command is identical to arrowto
 except that the displacement is specified relative to the
 current point. More than one coordinate point can be
 specified in the command in which case a series of line
 segments terminated by arrows connecting the points will be
 added to the current path. If there is no current point
 then an error will be generated. The size of the arrow
 head may be changed with the set(FONTWIDTH,...); command.

<readdata>
 void readdata(char * filename, double * data);

 Reads a file of name filename and puts the data into the
 array "data". The file should be in ASCII format with the x
 data in one column and the y data values next column(s).
 Any line containing non numeric characters or is blank will
 be considered a comment and ignored. WARNING! As an
 optimization data is only read from disk once if the
 configuration parameter always_load is off. Subsequent
 executions use the stored data already in memory (except
 after a reset). This means that if you modify the array
 "data" after reading in values the next time the file is
 executed you will get strange results. Similarly, if you
 reuse the same array for different plots in the same
 drawing you will have trouble. The motto is never change
 the values in the array "data". If you want to change the
 values declare another array and copy the values. Also
 remember that readdata() implicitly allocates memory for
 the data array so it is correct to declare the data array
 as double *data; at the top. If however, you are going to
 fill in a new array with calculated values you need to
 declare the array as double newdata[ysize][xsize]; so that
 space will be allocated.


<reset>
 void reset();

 Restores all set able parameters to their default values.
 Clears the current path and clip path.

<rlineto>
 void rlineto(double x,double y,...);

 Adds a line segment to the current path from the current
 point to the current point plus x, y. This command is
 identical to lineto except that the displacement is
 specified relative to the current point. More than one
 coordinate point can be specified in the command in which
 case a series of line segments connecting the points will
 be added to the current path. If there is no current point
 then an error will be generated.

<rmoveto>
 void rmoveto(double x, double y);

 Sets the current point to the current point plus x,y. This
 command is the same as moveto except that a relative move
 is specified. It also sets the path close point for
 subsequent use with closepath(). Many path building
 commands such as curveto and lineto require that a current
 point exist before calling them.

<rotate>
 void rotate(double ang);

 Rotates the figure about the
 current origin by the the angle
 specified. The angle units are
 degrees and the +ve direction
 is counterclockwise.
 Changes in rotation are cumulative.

<scale>
 void scale(double xs, double ys);

 Changes the scale of the figure
 by the factors specified for
 the x and y axes respectively.
 Changes in scale are cumulative.

<set>
 void set(int option, ...);

 All set able parameters can be set using the set command.
 The first parameter specifies which option to set. The
 defined constants corresponding to valid options are
 defined in the header file splot.h. What follows is a very
 brief description of all the values set able using set().

 set(AXESCLIP,val);
 If val is ON then the data values are clipped to the limits
 of the axes box. This is temporarily added to the user set
 clip limits if any. If val is OFF (the default) then the
 user specified clip limits from the last clip() call are
 used.
 Alternatively the range of data values plotted can be set
 using set(XRANGE,...); set(YRANGE,...); .

 set(AXESTYPE,val);
 AXESTYPE may be one of the following. LINEAR (the default),
 LOGX, LOGY, LOGLOG, INVX, INVY, INVINV, INVXLOGY or
 LOGXINVY. The position of data points and tickmarks are
 automatically adjusted to account for the axes type.

 set(CURSYMBOL,sym);
 Sets the symbol to use when plotting data with symbols. sym
 must be one of OCIRCLE,OSQUARE,OTRIANGLE,ODIAMOND
 OSTAR,OARROW,PLUS,CROSS,MULT,CIRCLE,SQUARE,TRIANGLE,
 DIAMOND,STAR,or ARROW. The default symbol is CIRCLE. The
 size of a symbol can be changed using set(FONTWIDTH,
 val_in_cm); since symbols are just a special font.
 The size of a symbol can be changed using set(FONTWIDTH,
 val_in_cm); since symbols are just a special font. The
 size relative to the current FONTWIDTH can be set using
 set(SYMMULT,mult);.

 set(FILLRULE,type);
 Determines the rule to be used when filling a path. Type
 must be one of NONZWIND (default) or EVENODD.

 set(FLATNESS,num);
 Sets the maximum allowable error in pixels when converting
 a curve to a set of straight line segments. Smaller values
 of num give smother curves but take longer to process. The
 default value of num is 1.

 set(FONT,fonttype);
 Sets the font type to use for subsequent text written using
 the text(); routine. fontname type be either SIMPLEX
 (default) or COMPLEX.

 set(FONTASPECT,asp);
 Sets the ratio of the glyph height to width used for text
 written using text();. The default value is 2.0

 set(FONTDIR,angle);
 Sets the rotation angle with respect to the x axis to use
 when writing text using text(); The default is 0.

 set(FONTMULT,factor);
 Multiplies the current font size by the given factor.

 set(FONTWIDTH,wid);
 Sets the average width of the characters written using
 text(). The default value is 0.7 cm. FONTWIDTH applies also
 to symbols.

 set(LABELMARG,val);
 Sets the additional margin between the axes box and the
 labels. The default is 0.0 cm.

 set(LINECAP,type);
 Determines how thick lines are to be terminated. The
 allowed types are BUTTCAP (default), ROUNDCAP and PROJCAP.

 set(LINECOLOUR,col);
 Where col is one of INVIS, BLACK, BLUE, GREEN, CYAN, RED,
 MAGENTA, BROWN or WHITE. This set the colour to use when
 the current path is stroked or filled. The default colour
 is BLACK with the background WHITE.

 set(LINEJOIN,type);
 Determines how thick lines are joined together. The allowed
 join types are MITERJOIN (default), BEVELJOIN and
 ROUNDJOIN.

 set(LINESTYLE,pattern,...);
 Sets the line style to use for the path when it is stroked.
 The constant LINESTYLE is followed by a list of floating
 point values that define the pattern. The values are
 interpreted as the length along the path that the line is
 visible followed by the length that it is invisible as an
 alternating sequence wrapping back to the beginning when
 the pattern reaches the end. For example a pattern of
 1.0,1.0 implies on for 1 cm followed by off for 1 cm. A
 pattern of 1.0,0.5 is on for 1 cm followed by off for 0.5
 cm. The predefined patterns are: SOLID 0 (default) DASHED
 1.0,0.5 DOTTED 0.2,0.2 and DOTDASH 1.0,0.5,0.2,0.5. There
 must always be an even number of comma separated values
 in a pattern definition.

 set(LINEWIDTH,width);
 Sets the line width to width cm (default 0.05 cm). This
 line width is used when the current path is stroked.

 set(MITERLIMIT,maxratio);
 Sets the maximum length of spikes formed by miter joining
 two lines at an acute angle. If the ratio of the length of
 the spike to the width exceeds the value of maxratio then a
 BEVELJOIN is done instead. The default value is 10.0.

 set(PAGEROT,flag);
 Selects landscape orientation if flag is ON.
 Default is portrait.

 set(PATTOFF,offset);
 Sets the offset into the current LINESTYLE pattern. Can be
 used to adjust the starting point of a pattern for aesthetic
 reasons.

 set(PLOTTYPE,type);
 Sets the current plot type. type must be one of LINES
 (default), SYMBOLS or SYM_LINES. LINES connects data points
 with line segments while SYMBOLS causes the current symbol
 to be drawn at each data point. SYM_LINES does both.
 The size of a symbol can be changed using set(FONTWIDTH,
 val_in_cm); since symbols are just a special font. The size
 relative to the current FONTWIDTH can be set using
 set(SYMMULT,mult);.

 set(SCALEALL,val);
 If val is ON then the XSHIFT, YSHIFT, XMULT, YMULT values
 are applied to all coordinates (i.e. in lineto, moveto etc.).
 The default is OFF in which case only data plotted using
 plotdata or drawdata is affected by these values.


 set(SCRIPTSCALE,val);
 Sets the relative height of a super/sub script as compared
 to ordinary text. The default value is 0.5.

 set(SCRIPTSHIFT,val);
 Sets the distance that a super/sub script is shifted
 above/below ordinary text. The value is specified as a
 fraction of the ordinary text height. The default value is
 0.7.

 set(SYMMULT,val)
 Sets the symbol size multiplier used when drawing symbols.
 The default value is 1.0. The actual symbol size is
 determined the current FONTWIDTH multiplied by the curent
 SYMMULT value.

 set(TICKLENGTH,len);
 Sets the length of axis tick marks to be used. The default
 value is 0.3 cm.

 set(TICKLMARG,len);
 Sets the margin between the axes box and the tick labels.
 The default is 0.0 cm.

 set(XMULT,xmul);
 Causes each x value to be multiplied by xmul before being
 plotted.

 set(XRANGE,xmin,ymin);
 data plotted using drawdata is constrained to have x
 values between xmin and xmax. There is also a corresponding
 YRANGE set option. The default is no constraints. The
 values should be specified in user coordinates i.e. those
 established by the current axes_box() or ascale().

 set(XSHIFT,xshft);
 Causes the value xshft to be added to all x values before
 plotting.

 set(YMULT,ymul);
 Causes each y value to be multiplied by ymul before being
 plotted.

 set(YSHIFT,yshft);
 Causes the value yshft to be added to all y values before
 plotting.


<showpage>
 void showpage();

 Transfers the marked page created in memory by the stroke
 and fill commands to the physical page. This is
 automatically done at the end of the file and thus this
 command is only needed if it is desirable to draw parts
 of the figure before the end of execution.

<stroke>
 void stroke();

 Marks the page in memory with the current path. The path
 coordinates are transformed using the current coordinate
 transformation matrix and the path is fleshed out using the
 current line width, style and colour in effect at the time
 of the stroke command.

<symbol>
 void symbol(double x, double y, int symbol_const);
 or
 void symbol(int symbol_const);

 Plots the symbol chosen by symbol_const at the point x,y.
 symbol_const must be one of OCIRCLE, OSQUARE, OTRIANGLE,
 ODIAMOND OSTAR, OARROW, PLUS, CROSS, MULT, CIRCLE, SQUARE,
 TRIANGLE, DIAMOND, STAR,or ARROW. If the point x,y is
 omitted the symbol is drawn at the current point as set
 by a previous moveto();. symbol() is not implicitly
 stroked so follow with a stroke();. The size of a symbol
 can be changed using set(FONTWIDTH, val_in_cm); since
 symbols are just a special font. The size relative to the
 current FONTWIDTH can be set using set(SYMMULT,mult);.

<text>
 void text(double x, double y, char * str,int just);

 Adds the text string str to the current path starting at
 location (x,y). The current font, size and orientation as
 set using the set() command are used. Super/sub scripts can
 be entered as ^2^ and _2_ respectively. Letters surrounded
 by '!' or '#' are printed in Greek or italics respectively.
 For example !m! generates the Greek lower case mu. The
 special characters "^_!#$\" can be printed by preceding them
 with \ as in \!. The combination \b back spaces by one
 character. Symbols may be included in the text string by
 enclosing them with $ as in $3$.
 If the starting x,y coordinates are omitted then
 the current string is positioned one line below the
 previous string added to the path using text(). The last
 parameter is the justification and must be one of LEFT,
 RIGHT or CENTER. This last parameter can be omitted in
 which case the default value of LEFT will be used. text()
 is implicitly stroked.

<ticklabel>
 void ticklabel(int axis, double v, char *label,...);

 Add tick labels to the axes box previously defined. The
 first parameter is which axis to label either BOTTOM, TOP,
 LEFT or RIGHT. The following parameters are paired values
 giving the tick position in data coordinates as established
 by a prior call to axes_box() or ascale() and the text
 string to be placed at that location. An error is generated
 if there is no current axes_box. There are several default
 possibilities. If 'ticklabel();' is called without any
 parameters then if tick marks have been generated
 previously using 'tickmarks();' then they will be
 selectively labelled along the left and bottom axes. If
 only an axis parameter is given then the corresponding axis
 tick marks if any will be labelled. If the axis parameter
 is followed by a list of numbers only they will be
 assumed to be both the tick position and the desired label.
 If the numbers are paired with strings in the parameter
 list then the number will be used as the tick label
 position and the string will be used as the literal label.
 The spacing between the tick labels and the axes box can be
 changed using set(TICKLMARG,...); ticklabel() is implicitly
 stroked.

<tickmarks>
 void tickmarks(int axis, double v,...);

 Add tick marks to the axes box previously defined. The
 first parameter is which axis either BOTTOM , TOP, LEFT,
 RIGHT ,XAXES or YAXES. The following numbers are the
 positions were tickmarks are to to be placed. The length of
 the ticks is set using a set(TICKLENGTH,val) command. The
 location of the ticks is specified in data coordinates as
 established by the prior call to axes_box(). An error is
 generated if there is no current axes_box. All the above
 parameters are optional. The default behaviour is as
 follows. If all parameters are omitted tick marks will be
 automatically generated for all axes. If only an axis
 specifier is given then tick marks will be generated for
 the corresponding axis or axes. In these cases
 'tickmarks();' will try to find reasonable positions for a
 set of tick marks. If this default behaviour is
 unacceptable then the actual tick positions can be
 specified as a list of values following the axis specifier.
 If there is only one numeric value it is interpreted as a
 tick spacing. tickmarks() is implicitly stroked.

<translate>
 void translate(double tx, double ty);

 Translates the origin of the
 figure by the x and y distances
 specified. Translations are
 cumulative.

<whereis>
 void whereis(double *x,double *y);

 Returns the coordinates of the current point as set by the
 last moveto(), lineto() etc.

<break>
 C keyword

 Used to prematurely terminate a loop;

 Example:

 for (i = 0;i< 100; i++)
    {
    if (cond == 1) break;
    /* if cond == 1 break out of the
    loop regardless of the value of
    i and continue at end of loop. */
    }

<case>
 C keyword

 Used in conjunction with a switch to select one of a set of
 choices.

 Example:

  switch(code)
     {
     case 0:/* do something if code = 0*/
        break;
     case 1:/* do this if code = 1*/
        break;
     case 2:
     case 3:/* do this if code = 1 or 2*/
        break;
     default:/* do this if none of the
           above */
       break;
     }

<char>
 C keyword

 Used to allocate memory for a variable of size one byte.
 All chars are between -128 and 127. All variable
 declarations must be done outside of the main routine for
 globals or immediately after the function declaration for
 local variables.

 Example:

  char c;

 Arrays of base types can be specified using the syntax:

  char tmp[80];

 Pointers to a base type are specified as

  char *tp;

<continue>
 C keyword

 Used to skip the remainder of a loop and test the condition
 again.

 Example:

 for (i = 0;i< 100; i++)
    {
    if (cond == 1) continue;
    /* if not cond == 1 do the rest
    of the loop below the above line
    otherwise increment i and test
    again.
    }


<default>
 C keyword

 Used in conjunction with a switch to select the remaining
 not explicitly specified choices.

 Example:

 switch(code)
    {
    case 0:/* do something if code = 0*/
       break;
    case 1:/* do this if code = 1*/
       break;
    case 2:
    case 3:/* do this if code = 1 or 2*/
       break;
    default:/* do this if none of the
           above */
       break;
    }

<do>
 C keyword

 Used in conjunction with while to set up loops that are
 executed at least once. For Example:

 do
    {
    /* loop body */
    }
 while (cond ==  1);

<double>
 C keyword

 Used to allocate memory for a double precision floating
 point value. All variable declarations must be done outside
 of the main routine for globals or immediately after the
 function declaration for local variables.

 Example:

 double d;

 Arrays of base types can be specified using the syntax (2 x
 400 array):

 double data[2][400];

 Pointers to a base type are specified as

 double *tp;

<else>
 C keyword

 Used as part of an if statement to select the converse
 case. Example

 if (cond == 1)
    {
    /* execute this if cond = 1 */
    }
 else
    {
    /* execute this if cond not 1 */
    }

<float>
 C keyword

 Used to allocate memory for a single precision floating
 point value. All variable declarations must be done outside
 of the main routine for globals or immediately after the
 function declaration for local variables.

 Example:

 float f;

 Arrays of base types can be specified using the syntax (2 x
 400 array):

 float data[2][400];

 Pointers to a base type are specified as:

 float *tp;

<for>
 C keyword

 Used to set up loops which are meant to run for a
 predetermined number of iterations. For example:

 for (i = 0;i< 100; i = i + 2)
    {
    /* execute this loop body 50
    times. i.e. until i = 100 with
    i starting at zero and incremented
    by 2 after each iteration */
    }

<int>
 C keyword

 Used to allocate memory for a variable of size one integer.
 All variable declarations must be done outside of the main
 routine for globals or immediately after the function
 declaration for local variables.

 Example:

 int i,j;

 Arrays of base types can be specified using the syntax (2 x
 400 array):

 int data[2][400];

 Pointers to a base type are specified
 as

 int *tp;

<if>
 C keyword

 Used to conditionally execute a block of code depending if
 the conditional expression is true (non zero) or false
 (zero). Can be used in conjunction with the keyword else.
 For example:

 if (i > j && k != 10)
    {
    /* execute this block if i greater
    than j and k not equal to 10 */
    }
 else
    {
    /* otherwise to this block */
    }

<main>
 C keyword

 This is actually a function and is the starting point of
 the code. The function main is called by hitting CTRL G.
 The syntax is

 main()
    {
    /* program to be executed */
    }

<return>
 C Keyword

 This exits a sub routine and returns an optional value to
 the calling routine. For example:

 main()
    {
    int x;
    i = sub(x);
    print(i);
    }

 int sub(int x)
    {
    /* calculate i based on input x */
    return i;
    }

<switch>
 C keyword

 Used to select one of a number of choices based on the
 value of the expression code.

 Example:

 switch(code)
    {
    case 0:/* do something if code = 0*/
       break;
    case 1:/* do this if code = 1*/
       break;
    case 2:
    case 3:/* do this if code = 1 or 2*/
       break;
    default:/* do this if none of the
           above */
       break;
    }

<while>
 C keyword

 Used to construct loops which run an non predetermined
 number of times. For example:

 cond = 1;
 while (code == 1)
    {
    /* execute this loop body until
    something in here sets cond to
    something other than 1. */
    }