Matplotlib is a plotting library for Python which uses syntax similar to
MATLAB.  The library provides a "pylab" interface which is procedural
and based on a state machine, like OpenGL.  There is also an OOP
interface which has less thorough documentation and greater complexity.
Using the OOP interface, matplotlib plots can be embedded in
applications using generic GUI toolkits like wxPython, Qt or GTK.

Matplotlib requires NumPy, which is also available at SlackBuilds.org.
Also, pygtk is an optional dependency.
