If you have any intention of continuing to install updated versions of matplotlib as they come along, then please start now to eliminate the use of the matplotlib.numerix subpackage, if you have not already done so. It has not been used internally in matplotlib, or made available via pylab, for well over a year.
In the next release of matplotlib based on the svn trunk, importing numerix will trigger a warning. In some later release, numerix will be removed entirely.
Note that the sole present function of numerix is essentially to make numpy behave like the old Numeric.