[SciPy-user] Interaction of sparse and dense matrices in scipy

Nils Wagner nwagner at mecha.uni-stuttgart.de
Tue Feb 21 06:04:20 CST 2006

Ed Schofield wrote:
>Nils Wagner wrote:
>>Hi Ed,
>>Thank you for your valuable comments.
>>The multiplication a*b, where a is dense a b is sparse, is certainly of
>>For example Block Krylov methods make heavily use of such products.
>>Anyway, it would be nice if scipy can handle such products :-)
>It does work now where 'a' is an *array*, but not when 'a' is a (dense)
>matrix.  For now, just use a dense array :)
>The reason is that the matrix object overrides the * operator and calls
>dot(a, b).  I'll think about this problem when I have time and make some
>proposals on scipy-dev and/or numpy-discussion for how to solve it...
>-- Ed
>SciPy-user mailing list
>SciPy-user at scipy.net
Hi Ed,

May I send you my (sparse/dense) codes for solving large Sylvester
The results of the dense version are o.k. while the sparse version
doesn't work as expected.
I hope you can drop some hints ;-) .



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