sympy/sympy — pull request #1166 by jrioux (2012-03-23 23:50:31+00:00)
Title: Fix latex printing of MatAdd and MatMul (issue 3183).

The latex printing for MatMul misses integer prefactors and for MatAdd includes leading + sign.

This is corrected and now:
>>> from sympy import *
>>> print latex(Integer(3)*ImmutableMatrix([1,2]))
3\left[\begin{smallmatrix}1\\2\end{smallmatrix}\right]
>>> print latex(Integer(3)*ImmutableMatrix([1,2])+ImmutableMatrix([10,20]))
\left[\begin{smallmatrix}10\\20\end{smallmatrix}\right] + 3 \left[\begin{smallmatrix}1\\2\end{smallmatrix}\right]

http://code.google.com/p/sympy/issues/detail?id=3183