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glplotter (version 2.0.0)

Screenshot from "glplotter"
Screenshot from "glplotter"
Screenshot from "glplotter"

glplotter draws graphs of mathematical functions. You specify a mathematical expression to be used as a function, using a straightforward syntax, like "sin(x) + x^2".

glplotter can also load a graph from a file. This is useful if your graph data doesn't come from any mathematical expression — e.g. maybe it's some collected statistical data. Maybe your data is not even a function at all — actually any shape consisting of line segments may be displayed by glplotter.

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  1. Command-line parameters
  2. Graph file format
  3. gen_function
  4. Syntax of mathematical expressions

1. Command-line parameters

You can pass at command-line file names from which to load graphs. Dash (-) as filename means "standard input".

E.g. you could pipe the output of gen_function program to glplotter, like

  gen_function "sin(x)" -10 10 0.1 | glplotter -
which will display the graph of sinus for X in [-10; 10]. Commands like
  gen_function "sin(x)" -10 10 0.1 > plot.1
  gen_function "x^2" -10 10 0.1 > plot.2
  glplotter plot.1 plot.2
will display graphs of sinus and x2 at once. Of course, in case of function expressions, it's usually more comfortable to set them up inside glplotter using "Functions" menu.

Options --light and --dark allow you to choose appropriate color scheme.

Option --custom-size SIZE (or -c SIZE) specifies size for

See also standard parameters of OpenGL programs and standard parameters of all programs.

2. Graph file format

Graph for glplotter is actually just a set of line segments. They don't have to correspond to any function — they can show any shape, they can cross each other etc.

File format:

Whitespace at the beginning and end of the line is always ignored.

3. gen_function

gen_function generates graph file from given function expression. It's seldom needed — glplotter can make a graph from function expression on it's own, see menu "Functions".

Call it like:

  gen_function <function> <x1> <x2> <xstep>

This will write on standard output the graph of function <function> for x in range [<x1> ; <x2>] (with x sampled at each <xstep> distance). The graph will be in format understood by glplotter.

For example

  gen_function "x^2" 0 5 1
will write
# File generated by gen_function on 14-3-2004 at 23:34:37
#   function = x^2
#   x1 = 0
#   x2 = 5
#   xstep = 1
 0.0000000000000000E+0000  0.0000000000000000E+0000
 1.0000000000000000E+0000  1.0000000000000000E+0000
 2.0000000000000000E+0000  4.0000000000000000E+0000
 3.0000000000000000E+0000  9.0000000000000000E+0000
 4.0000000000000000E+0000  1.6000000000000000E+0001
 5.0000000000000000E+0000  2.5000000000000000E+0001

4. Syntax of mathematical expressions

Short overview of mathematical expressions syntax: this is really just normal syntax of mathematical expressions, as used in all software and resembling normal mathematical notation. When we deal with function expressions, then x represents the argument, e.g. (x+4)*3+2, sin(x) etc.

For detailed information about syntax and built-in functions, see CastleScript language reference. We use a subset of CastleScript syntax, allowing only a simple expression as a function expression, operating on argument "X".