[Numpy-discussion] Sparse matrices in NumPy?

[Paul Gettings]

I have a problem where I need to do matrix multiplication of a 7731x7731
matrix; storing this thing would take over 250 MB of memory, which is more
than my machine has. :(  However, the matrix is empty except for the main
diagonal.  Ideally, all that needs to be stored is a single vector 7731
elements long, and then tweak matrix multiplication algorithms to account for
this.  Are there any facilities in NumPy to do this sort of thing, or do I
have to roll my own?  Is there a way to effeciently store a very sparse
matrix and do standard matrix multiplies?  Thanks.

	-Paul Gettings
	 Dep't of Geology & Geophysics
	 University of Utah
--
  But Your Honor, they needed killin'.