I believe I've hit the bug noted in the 2004-07-28 matplotlib-users post
with a subject "plot dense and large array, AGG limit?".
I'm wondering if there has been a work around identified. I looked for a
follow up in the matplotlib lists as well as the vector-agg-general list.
I've tried to use cairo, but I'm having problems getting my mathtext to
work, even after setting my numerix to numpy.
Any help would be appreciated as I'd like to use matplotlib to make
figures for a manuscript I'm writing.