[petsc-users] Does PETSc have some functions like A.*B, A./B in Matlab?

Yujie recrusader at gmail.com
Sun Feb 21 14:50:40 CST 2010

Sorry, I made a mistake, it should be A is sparse matrix and  B is dense


On Sun, Feb 21, 2010 at 2:44 PM, Yujie <recrusader at gmail.com> wrote:

> I need do it for many. Actually, we don't consider a vector. Generally, if
> A is dense matrix (nonzero entries) and B is sparse matrix, MatGetRow()
> doesn't work when doing A.*B or A./B directly, right?
> Thanks a lot.
> Regards,
> Yujie
> On Sun, Feb 21, 2010 at 2:41 PM, Jed Brown <jed at 59a2.org> wrote:
>> On Sun, 21 Feb 2010 14:33:23 -0600, Yujie <recrusader at gmail.com> wrote:
>> > Thanks very much, Jed.
>> > I have a vector (V) and a matrix (A),
>> > I want to do Row_i_A.*V or Row_i_A./V (Row_i_A are the rows of A).
>> However,
>> > V has different format with the rows of A.
>> You need to do this for a small number of rows (values of i), or for
>> many?  Since vectors are dense, and since MatGetValues only provides the
>> local part, this is not scalable.
>> What is the problem you are trying to solve with this algebraic
>> manipulation?  There is probably a scalable way to formulate the
>> higher-level objective to avoid these shenanigans.
>> Jed
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