add description for matplotlib

Author: daler

docs/scenarios/scientific.rst

@@ -40,7 +40,12 @@ scientific python has never been easier (one click to install about 100 scientif
 Matplotlib
 ----------
 
-.. todo:: write about matplotlib.
+`matplotlib <http://matplotlib.sourceforge.net/>`_ is a flexible plotting library
+for creating interactive 2D and 3D plots that can also be saved as manuscript-quality
+figures.  The API in many ways reflects that of `MATLAB <http://www.mathworks.com/products/matlab/>`_, easing transition of MATLAB
+users to Python.  Many examples, along with the source code to re-create them,
+can be browsed at the `matplotlib gallery <http://matplotlib.sourceforge.net/gallery.html>`_.
+
 
 PyQwt
 -----