[Matrix-SIG] Sparse objects

[Travis Oliphant]

An anonymous reader asks this valid question?

> Why not wrap the Yale Sparse Matrix package or something from netlib and be
> done with it?

This is a good suggestion and has already been done to some degree with
Neil Schemenauer's sparsemodule which defines a sparse matrix
object in wrapping a sparse LU solver available on netlib.  As I was
looking at it the structure is highly dependent on that used by the
wrapped-library and so it is not directly useful for an iterative solver.
I didn't want to just repeat this and have another only-useful-here
implementation.

Matlab has a sparse matrix object that is integrated quite nicely in the
language along with some routines which allow for easy construction of
sparse matrices so that any iterative algorithm can be rapidly implemented
in the MATLAB language.  

I don't think it would be that difficult to replicate MATLAB's
functionality.  I posted here before just doing it because I know this is
a popular subject and other's would have some good ideas.  Plus, this
gives someone else the "chance" to get intimate with Python's and Numeric
Python's guts by writing C-code which interacts with it.

In this case, it seems like we could define a UserArray that acts like a
Sparse Matrix.  We would likely want some of the operations coded in C but
this may be the way to go, rather than defining a new type in C.   Does
anybody see any obvious problems with this?

I'm under the impression that the Yale Sparse Matrix package is only
available if you own an IMSL license.  Can anybody verify that?

Travis