use of the SciPy Array Interface

this doesn't: matshow(matrix([[1.0,2.0],[3.0,4.0]]) but

    > this does
    > matshow(pylab.array(matrix([[1.0,2.0],[3.0,4.0]])

These should be considered bugs -- we should do an asarray anywhere we
are expecting an array input. I fixed matshow in svn -- let us know
if you find others, or send a patch. They are easy to fix.