[SciPy-dev] Tri-diagonal LAPACK Routines - Shall I interface them?
David Warde-Farley
dwf@cs.toronto....
Wed Dec 2 14:48:53 CST 2009
On 2-Dec-09, at 3:43 AM, Benny Malengier wrote:
> would be a type of sparse matrix one can manipulate. This would allow
> things like changing matrix diagonal orded form sparse matrix to a csr
> matrix, adding some extra elements off the diagonals, and then calling
> a more generic solver.
Well, often when people talk about sparse matrices they mean (often
unstructured) matrices that are _very_ sparse, like, large systems
with a very small fraction of the matrix elements non-zero. Banded
systems don't really fit in this kind of way of thinking because they
are a) structured and b) relatively dense. That said, I'm not certain
there are any strong feelings on the matter from the maintainers of
scipy.sparse, so if you'd like to see this kind of functionality you
might as well open a ticket and submit a patch.
Note that converting to CSR and then adding elements would probably be
an inefficient way to do it. In general the compressed formats don't
lend themselves to insertion; dok_matrix might be a better bet, with a
conversion to CSR when you freeze the contents.
David
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