Usenet 1994 October/usenetsourcesnewsgroupsinfomagicoctober1994disk2.iso/misc/volume8/gnuplot1.10A/part06/docs/gnuplot.hlp

Text File | 1989-09-09 | 19.2 KB | 583 lines

 GNUPLOT is a command-driven interactive function plotting program.  It
 is case sensitive (commands and function names written in lowercase
 are not the same as those written in CAPS).  All command names may be
 abbreviated, as long as the abbreviation is not ambiguous.  Any number
 of commands may appear on a line, separated by semicolons (;).

 Type the EOF character (^D for UNIX, ^Z for DOS) to exit the help system
 from any level and return to GNUPLOT.  <RETURN> goes back to the previous
 level and to GNUPLOT from top level help.
1 clear
 This command erases the current screen or output device as specified
 by 'set output'.  This usually generates a formfeed on hardcopy
 devices.  Use 'set terminal' to set the device type.
1 exit
 'exit', 'quit' and your computer's END-OF-FILE character will exit
 GNUPLOT.  All these commands will clear the output device (as the
 'clear' command does) before exiting.
1 expressions
2 functions
3 abs
 This function returns the absolute value of its argument.  The
 returned value is of the same type as the argument.

 For complex arguments, abs(x) is defined as the length of x in the
 complex plane [i.e.  sqrt(real(x)**2 + imag(x)**2) ].
3 acos
 This function returns the arc cosine (inverse cosine) of its
 argument.  'acos' returns its argument in radians.
3 arg
 This function returns the phase of a complex number, in radians.
3 asin
 This function returns the arc sin (inverse sin) of its argument.
 'asin' returns its argument in radians.
3 atan
 This function returns the arc tangent (inverse tangent) of its
 argument.  'atan' returns its argument in radians.
3 besj0
 This function returns the j0th Bessel function of its argument.
 'besj0' expects its argument to be in radians.
3 besj1
 This function returns the j1st Bessel function of its argument.
 'besj1' expects its argument to be in radians.
3 besy0
 This function returns the y0th Bessel function of its argument.
 'besy0' expects its argument to be in radians.
3 besy1
 This function returns the y1st Bessel function of its argument.
 'besy1' expects its argument to be in radians.
3 ceil
 This function returns the largest integer not less than its
 argument.  For complex numbers, 'ceil' returns the largest integer
 not less than the real part of its argument.
3 cos
 This function returns the cosine of its argument.  'cos' expects its
 argument to be in radians.
3 cosh
 This function returns the hyperbolic cosine of its argument.
 'cosh' expects its argument to be in radians.
3 exp
 This function returns the exponential function of its argument
 (e raised to the power of its argument).
3 floor
 This function returns the smallest integer not greater than its
 argument.  For complex numbers, 'floor' returns the smallest
 integer not greater than the real part of its argument.
3 imag
 This function returns the imaginary part of its argument as a real number.
3 int
 This function returns the integer part of its argument, truncated
 toward zero.
3 log
 This function returns the natural logarithm (base e) of its
 argument.
3 log10
 This function returns the logarithm (base 10) of its argument.
3 real
 This function returns the real part of its argument.
3 sgn
 This function returns 1 if its argument is positive, -1 if its
 argument is negative, and 0 if its argument is 0.  If the argument
 is a complex value, the imaginary component is ignored.
3 sin
 This function returns the sine of its argument.  'sin' expects its
 argument to be in radians.
3 sinh
 This function returns the hyperbolic sine of its argument.  'sinh'
 expects its argument to be in radians.
3 sqrt
 This function returns the square root of its argument.
3 tan
 This function returns the tangent of its argument.  'tan' expects
 its argument to be in radians.
3 tanh
 This function returns the hyperbolic tangent of its argument.
 'tanh' expects its argument to be in radians.
2 operators
3 binary
 The following is a list of all the binary operators and their
 usages:

  Symbol     Example      Explanation
   **          a**b          exponentiation
   *           a*b           multiplication
   /           a/b           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
   ?:          a?b:c       * ternary operation

 (*) Starred explanations indicate that the 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.

 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.
3 unary
 The following is a list of all the unary operators and their
 usages:

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

 (*) Starred explanations indicate that the operator requires an
 integer argument.

 The factorial operator returns a real number to allow a greater range.
1 help
 The 'help' command displays on-line help.  To specify information on a
 particular topic use the syntax:

     help <topic>

 Help is actually a separate program.  If help doesn't work for you, ask
 your administrator how to set up the GNUHELP environment variable (and
 possibly the HELPDIR environment variable).

 You may exit the help utility and return to GNUPLOT by either pressing
 <Return>(s) at the 'HELP >' prompt or pressing your computer's END-OF-FILE
 character at any help prompt.
1 load
 This command executes each line of the specified input file as if it
 had been typed in interactively.  Files created by the 'save' command
 can later be 'load'ed.  Any text file containing valid commands can be
 created and then executed by the 'load' command.  Files being 'load'ed
 may themselves contain 'load' commands.  Lines beginning with # (or !
 if using VMS) will be treated as comments and ignored.

 The 'load' command must be the last command on the line.

 Syntax:
         load <input-file>

 The name of the input file must be enclosed in quotes.

 Examples:

         load 'work.gnu'
         load "func.dat"
1 pause
 Pause is useful in conjunction with `load` files.  The command 'pause'
 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 is an expression that can be -1, 0, 1, 2, ...  -1
 will wait until a carriage return is hit.  0 won't pause at all, and
 1, 2, etc. will wait the specified number of seconds.

 Note: Since pause is not part of the plot it may interact with
 different device drivers differently (depending upon how text and
 graphics are mixed).

 Examples:
         pause -1    ! Wait until a carriage return is hit
         pause 3     ! Wait three seconds
         pause -1  "Hit return to continue"
         pause 10  "Isn't this pretty?  It's a cubic-spline."

 Syntax:
         pause <expression> ["string"]
1 plot
2 data_file
 Discrete data contained in a file can displayed by specifying the
 name of the data file (enclosed in quotes) on the 'plot' command
 line.

 Data files should contain one data point per line.  A data point may
 be specified either as an X and Y value separated by blank space, or
 as just the Y value, in which case the program will use the number
 of the coordinate as the X value.  Coordinate numbers starts at 0
 and are incremented for each data point read.  Blank lines and lines
 beginning with # will be treated as comments and ignored.


 This example compares the data in the file population.dat to a
 theoretical curve:

         pop(x) = 103*exp((1965-x)/10)
         plot [1960:1990] 'population.dat', pop(x)

 The file population.dat might contain:

  # Gnu population in Antarctica since 1965
  1965   103
  1970   55
  1975   34
  1980   24
  1985   10
2 ranges
 This option specifies the region of the plot which will be displayed.

 Ranges may be provided on the 'plot' command line as synonyms for
 the 'set xrange' and 'set yrange' commands.

 Syntax:
         [{dummy-var =} {xmin : xmax}] { [{ymin : ymax}] }

 Where dummy-var is the independent variable (the default is 'x',
 but this may be changed with the 'set dummy' command) and the min
 and max terms can be expressions or constants.

 Both the min and max terms are optional.  The ':' is also optional
 if neither a min nor a max term is specified.  This allows '[]' to
 be used as a null range specification.

 Specifying a Y range turns autoscaling OFF.


 Examples:

 This uses current ranges:
         plot cos(x)

 This sets the xrange only:
         plot [-10:30] sin(pi*x)/(pi*x)

 This is the same, but uses t as the dummy-variable:
         plot [t = -10 :30]  sin(pi*t)/(pi*t)

 This sets both the x and yranges:
         plot [-pi:pi] [-3:3]  tan(x), 1/x

 This sets only the yrange:
         plot [] [-2:sin(5)*-8] sin(x)**besj0(x)

 This sets xmax and ymin only:
         plot [:200] [-pi:]  exp(sin(x))
2 style
 Plots may be displayed in one of three styles: 'lines', 'points', or
 'impulses'.  The 'lines' style connects adjacent points with lines.
 The 'points' style displays a small symbol at each point.  The
 'impulses' style displays a vertical line from the X axis to each
 point.

 Default styles are chosen with the 'set function style' and
 'set data style' commands.

 Syntax:
         with <style>

 Where <style> is one of 'lines', 'points', or 'impulses'.  These
 keywords may be abbreviated.


 Examples:

 This plots sin(x) with impulses:
         plot sin(x) with impulses

 This plots sin(x) with points, cos(x) default:
         plot [-9:30]  sin(x) w points, cos(x)

 This plots tan(x) with the default function style, "data.1" with lines:
         plot [] [-2:5] tan(x), "data.1" with l

 This plots "leastsq.dat" with impulses:
         plot 'leastsq.dat' w i
1 print
 This command prints the value of <expression> to the screen.

 Syntax:
         print <expression>

 See 'expressions'.
1 quit
 'quit' is a synonym for 'exit'.  See 'exit'.
1 replot
 'replot' repeats the last 'plot' command.  This can be useful for
 viewing a plot with different 'set' options, or when generating the
 same plot for several devices.
1 save
 This command saves either user-defined functions, variables, or both
 to the specified file.

 Syntax:
         save  {option} <filename>

 Where <option> is either 'functions' or 'variables'.  If no option is
 used GNUPLOT saves both functions and variables.

 'save'd files are written in text format and may be read by the 'load'
 command.

 The filename must be enclosed in quotes.

 Examples:

         save "work.gnu"
         save functions 'func.dat'
         save var 'var.dat'
1 set-show
 Set or show various internal gnuplot settings.
2 all
 The command 'show all' will display all the set-show options
 currently in effect.

 Syntax:
         show all
2 autoscale
 If autoscaling is set, the Y axis is automatically scaled to fit the
 range of the function or data being plotted.  If autoscaling is not
 set, the current Y range is used.  See 'set yrange'.

 Syntax:
         set autoscale
         set noautoscale
         show autoscale
2 dummy
 By default, GNUPLOT assumes that the independent variable is 'x' on
 the 'plot' command line.  'x' is called the dummy variable because
 it is just a notation to indicate the independent variable.  The
 'set dummy' command changes this default dummy variable name.  For
 example, you may find it more convenient to call the dummy variable
 't' when plotting time functions:

         set dummy t
         plot sin(t), cos(t)

 Syntax:
         set dummy <dummy-var>
         show dummy
2 functions
 The 'show functions' command lists all user-defined functions and
 their definitions.

 Syntax:
         show functions
2 logscale
 Log scaling may be set on the X and/or Y axis.

 Syntax:
         set logscale <axes>
         set nologscale
         show logscale

 Where <axes> is either 'x', 'y', or 'xy'.
2 polar
 The 'set polar' command changes the meaning of the plot from
 rectangular coordinates to polar coordinates.  In polar
 coordinates, the dummy variable (x) is an angle.  The domain
 of this angle is changed from whatever it was to [0:2*pi].

 The command 'set nopolar' changes the meaning of the plot back
 to the default rectangular coordinate system.  The domain of
 x is changed from whatever it was to [-10:10].

 While in polar coordinates the meaning of an expression in x
 is really r = f(x), where x is an angle of rotation.  The plot,
 however, is plotted on a rectangular grid.  Thus the displayed
 ranges of x and y are rectanglar values, while the command
 'set xrange' refers to polar values.

 Syntax:
         set polar
      set nopolar
      show polar
2 offsets
 The amount of the graph that the plot takes up may be controlled
 to some extent with the 'set offsets' command.  This command takes
 four arguments--left offset, right offset, top offset and bottom
 offset.  By default, each offset is 0.  Left and right offsets are
 given in units of the x axis, while top and bottom offsets are
 given in units of the y axis.  The plot of sin(x), displayed with
 offsets of 0, 0, 2, 2 will take up  1/3 of the displayed y axis.
 Offsets are particularly useful with polar coordinates as a means
 of compensating for aspect ratio distortion.

 Syntax:
         set offsets <expr>, <expr>, <expr>, <expr>
         show offsets
2 output
 By default, plots are displayed to the standard output.  The
 'set output' command redirects the displays to the specified file or
 device.

 Syntax:
         set output {filename}
         show output

 The filename must be enclosed in quotes.  If the filename is
 omitted, output will be sent to the standard output.
2 samples
 The sampling rate of functions may be changed by the 'set samples'
 command.  By default, sampling is set to 160 points.  A higher
 sampling rate will produce more accurate plots, but will take
 longer.  In generating plots, GNUPLOT will use either the sampling
 rate set or the resolution of the current output device, whichever
 is lower.

 Syntax:
         set samples <expression>
         show samples
2 style
 Plots may be displayed in one of three styles: 'lines', 'points', or
 'impulses'.  The 'lines' style connects adjacent points with lines.
 The 'points' style displays a small symbol at each point.  The
 'impulses' style displays a vertical line from the X axis to each
 point.

 Default styles are chosen with the 'set function style' and 'set
 data style' commands.  See 'plot' for information about how to
 override the default plotting style for individual functions.

 Syntax:
         set function style <style>
         set data style <style>
         show function style
         show data style

 Where style is either 'lines', 'points', or 'impulses'.
2 terminal
 GNUPLOT supports many different graphics devices.  Use the 'set
 terminal' command to select the type of device for which GNUPLOT
 will produce output.   While your installation may not include all
 of these, the following were available in the source code at the
 time this help file was written:

 Machines:  IBM-PC's (ega, cga, hercules), ATT6300, CORONA325,
            UNIXPC (att7300 or 3b1);
 Terminals: AED512, AED767, HP2623A, HP7580B, REGIS, SELENAR,
            TEK40xx, BBN Bitgraph;
 Printers:  LASERJET1, LASERJET2, LASERJET3, POSTSCRIPT, QMS,
            VECTRIX384;
 Other:     UNIXPLOT.

 Syntax:
         set terminal {terminal-type}
         show terminal

 If <terminal-type> is omitted, GNUPLOT will list the available
 terminal types.  <terminal-type> may be abbreviated.

 Use 'set output' to redirect this output to a file or device.
2 variables
 The 'show variables' command lists all user-defined variables and
 their values.

 Syntax:
         show variables
2 version
 Show the current version of gnuplot.  This is the same text
 that appears when gnuplot starts up.  (There is no SET VERSION
 command, of course.)

 Syntax:
     SHOW VERSION
2 xrange
 The 'set xrange' command sets the horizontal range which will be
 displayed.

 This range may also be specified on the 'plot' command line.

 Syntax:
         set xrange [{xmin : xmax}]

 Where <xmin> and <xmax> terms are expressions or constants.

 Both the <xmin> and <xmax> terms are optional.
2 yrange
 The 'set yrange' command sets the vertical range which will be
 displayed.  This command turns autoscaling OFF.

 This range may also be specified on the 'plot' command line.

 Syntax:
         set yrange [{ymin : ymax}]

 Where <ymin> and <ymax> terms are expressions or constants.

 Both the <ymin> and <ymax> terms are optional.
2 zero
 GNUPLOT will not plot a point if its imaginary part is greater in
 magnitude than the 'zero' threshold.  The default 'zero' value is
 1e-8.

 Syntax:
         set zero <expression>
         show zero
1 shell
 The 'shell' command spawns an interactive shell.  To return to
 GNUPLOT, type 'logout' if using VMS, 'exit' or your END-OF-FILE
 character if using Unix, or 'exit' if using MS-DOS.

 A single shell command may be spawned by preceding it with the !
 character ($ if using VMS) at the beginning of a command line.
 Control will return immediately to GNUPLOT after this command is
 executed.  For example,

      ! dir

 prints a directory listing and then returns to GNUPLOT.
1 start_up
 When GNUPLOT is run, it looks for an initialization file to load.
 This file is called '.gnuplot' on Unix systems, and 'GNUPLOT.INI' on
 other systems.  If this file is not found in the current directory,
 the program will look for it in your home directory (under MS-DOS, the
 environment variable GNUPLOT should contain the name of this
 directory).

 If this file is found, GNUPLOT executes the commands in this file.
 This is most useful for setting your terminal type and defining any
 functions or variables which you use often.  The variable 'pi' is
 already defined for you.
1 substitution
 Command-line substitution is specified by a system command enclosed in
 backquotes (`).  This command is spawned and the output it produces
 replaces the name of the command (and backquotes) on the command line.

 Newlines in the output produced by the spawned command are replaced with
 blanks.

 Command-line substitution can be used anywhere on the GNUPLOT command
 line.


 Example:

 This will run the program 'leastsq' and substitute `leastsq` on the
 command line with its output:

  f(x) = `leastsq`

 or, in VMS

  f(x) = `run leastsq`
1 user_defined
 You may define your own functions and variables.  User-defined
 functions and variables may be used anywhere.

 User-defined function syntax:
     <function-name> ( <dummy-var> ) =  <expression>

 Where <expression> is defined in terms of <dummy-var>.

 User-defined variable syntax:
     <variable-name> = <constant-expression>

 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

 The variable 'pi' is already defined for you.

 See 'show functions' and 'show variables'.