Gnuplot OX server Manual

Edition : auto generated by oxgentexi on May 1, 2025

@overfullrule=0pt

1 GNUPLOT Functions

This chapter describes interface functions for GNUPLOT ox server ox_sm1_gnuplot. These interface functions are defined in the file gnuplot. The file ‘gnuplot.rr’ is at
‘$(OpenXM_HOME)/lib/asir-contrib’.

[255] gnuplot.start();
0
[257] gnuplot.gnuplot("plot sin(x**2);");
0

The function gnuplot.heat(dt,step) demonstrates our gnuplot interface. It numerically solves the heat equation The segment [0,1] is devided into Heat_N segments. The static variable Heat_N can be set by the function gnuplot.heat_set_N. If the celebrated Courant-Friedrichs-Levi number dt*Heat_N*Heat_N is less than or equal to 0.5, then the explicit scheme is numerically stable. One can observe the instability by changing CFL number.

  gnuplot.heat_set_N(20); gnuplot.heat(0.001,30);   (CFL number is 0.4)
  gnuplot.heat_set_N(20); gnuplot.heat(0.003,30);   (CFL > 0.5 unstable)

Author of GNUPLOT: Thomas Williams, Colin Kelley. http://www.gnuplot.info

1.1 Functions

1.1.1 gnuplot.start

gnuplot.start()

:: Start ox_sm1_gnuplot on the localhost.

return

Integer

• Start ox_sm1_gnuplot on the localhost. It returns the descriptor of ox_sm1_gnuplot.
• Set Xm_noX = 1 to start ox_sm1_gnuplot without a debug window.
• The descriptor is stored in Gnuplot_proc.

P = gnuplot.start();

Reference

ox_launch, gnuplot

1.1.2 gnuplot

gnuplot.gnuplot(s|proc=p)

:: Ask GNUPLOT to execute the command string s.

return

Void

p

Number

s

String

• The server executes the gnuplot command s. When an error occurs, the gnuplot itself terminates and ox_sm1_gnuplot server automatically restarts gnuplot.
• gnuplot does not accept a long polynomial.
• gnuplot does not accept ^. Use ** instead.

[232] P = gnuplot.start();
0
*Plot 3 dimensional graph.
[233] gnuplot.gnuplot("splot x**2-y**2;"|proc=P);
0
*Plot 2 dimensional graph.
[234] gnuplot.gnuplot("plot [-pi:pi] [-2:2] cos(x);");
0
*Output a graph as a postscript figure.
[235] gnuplot.output(|file="hoge.eps");
0
[236] gnuplot.gnuplot("plot sin(x)*cos(x);");
0
[237] gnuplot.gnuplot(|file="x11");
0

*Plot 3 dimensional graph hiding unvisible lines.
[236] gnuplot.gnuplot("set hidden3d");
0
[237] gnuplot.gnuplot("splot (x**2+y**2)*sin(x**2+y**2)");
0
[238] gnuplot.gnuplot("set isosamples 50");
0
[239] gnuplot.gnuplot("splot (x**2+y**2)*sin(x**2+y**2)");

Reference

ox_launch, gnuplot.start, rtostr, gnuplot.plot_dots

Reference Book

Yabuki Michiro, Otake Tuyoshi; Tukai konasu GNUPLOT, Techno Press, in Japansese, ISBN4-924998-11-7

1.1.3 gnuplot.plot_dots

gnuplot.plot_dots(d,s|proc=p)

:: Plot the dots d with the style s.

return

Void

p

Number

d

List

s

String or 0

• Plot the dots d with the style s. s is a string of the form "style color point". Here, style can be lines, points, linespoints, impulses, dots, steps, errorbars, boxes, boxerrorbars. color can be 1 (red), 2 (green), 3 (blue), 4, ... , 8. point can be a number from 1 to 8. The color and point field can be omitted.
• When d == [ ], the screen will be cleared.

[239] P = gnuplot.start();
0
[240] gnuplot.plot_dots([ ],0);            
0
[241] for (I=0; I<10; I++) gnuplot.plot_dots([[I,I^2]]," lines ");
[242] A = [ ];
[]
[243] for (I=0; I<10; I++) A = append(A,[ [I,I^2]]);
[244] A;
[[0,0],[1,1],[2,4],[3,9],[4,16],[5,25],[6,36],[7,49],[8,64],[9,81]]
[245] gnuplot.plot_dots(A," lines ");
0

Reference

gnuplot.start, plot "fileName" with options(GNUPLOT command), gnuplot.clean, gnuplot

1.1.4 gnuplot.heat

gnuplot.heat(dt,step)

:: It solves the heat equation numerical and plots solutions

return

Void

dt

floating point number

step

Integer

• It solves the heat equation du/dt = d^2 u/dx^2, u(t,0) = u(t,1) = 0 with the initial condition u(0,x) = x (0 <= x <= 0.5), u(0,x) = 1-x ( 0.5 <= x <= 1.0).
• Heat_N is the number of the meshes in the space.
• This function will be called pde_heat_demo in a future.

Algorithm: NOT Written. (Difference scheme. Courant-Levi-Friedrichs conditions.)

[232] gnuplot.set_heat_N(20)$ 
[233] gnuplot.heat(0.001,30)$

1.1.5 gnuplot.output

gnuplot.output(|file=s)

:: ask GNUPLOT to output graphic to the file s in the Postscript format.

return

Void

s

String

• ask GNUPLOT to output graphic to the file s in the Postscript format.
• When s is "x11" or this function is called without the argument, the output will be written to X11 display.

[273] gnuplot.output(|file="hoge.eps");
Graphic output of GNUPLOT will be written to hoge.eps as a Poscript file.
0
[274] gnuplot.gnuplot("plot tan(x)+sin(x);");
0
[275] gnuplot.output();
Usage of gnuplot.output: gnuplot.output(|file="string")
                         gnuplot.output(|file="x11")
Output device is set to X11

Reference

gnuplot

1.1.6 gnuplot.plot_function

gnuplot.gnuplot(f|proc=p)

:: ask the gnuplot server to draw a graph of f

return

Void

p

Number

f

Polynomial or a list of polynomials

• ask the gnuplot server to draw a graph of f

[290] gnuplot.plot_function((x+sin(x))^2);
0
[291] gnuplot.plot_function([x,x^2,x^3]);
0

Reference

gnuplot.to_gnuplot_format

1.1.7 gnuplot.stop

gnuplot.stop()

:: Stop the gnuplot and remove the temporary fifo file.

return

Void

s

String

• Stop the GNUPLOT and remove the temporary fifo file generated by the mkfifo system call under the temporary directory.

[273] gnuplot.stop()

Reference

gnuplot.start

1.1.8 gnuplot.setenv

gnuplot.setenv(key,value)

::

return

Void

key

String

value

Object

• The key takes the value either in "gnuplot.callingMethod" or "plot.gnuplotexec".

   Use the old method to communicate with gnuplot (version 3).
   This method does not use mkfifo, but we need a patched version of gnuplot.
[273] gnuplot.setenv("gnuplot.callingMethod",0);
[274] gnuplot.setenv("plot.gnuplotexec",getenv("OpenXM_HOME")+"/bin/gnuplot4ox");

   Calling your own gnuplot binary. 
[274] gnuplot.setenv("plot.gnuplotexec","/cygdrive/c/program files/gnuplot/pgnuplot.exe");

Reference

gnuplot.start

Index

Table of Contents

Short Table of Contents

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