[petsc-users] I am wondering if there is a way to implement SPMM

[Cong Li]

Hi

As I answered in the last email.
Actually, I am trying to implement s-step block krylov subspace method. So,
I need to expand the Krylov subspace by putting matrix polynomials into
another matrix.

Cong Li

On Tue, Aug 4, 2015 at 6:50 PM, Matthew Knepley <knepley at gmail.com> wrote:

> On Tue, Aug 4, 2015 at 4:09 AM, Cong Li <solvercorleone at gmail.com> wrote:
>
>> I am sorry that I should have explained it more clearly.
>> Actually I want to compute a recurrence.
>>
>> Like, I want to firstly compute A*X1=B1, and then calculate A*B1=B2,
>> A*B2=B3 and so on.
>> Finally I want to combine all these results into a bigger matrix C=[B1,B2
>> ...]
>>
>> Is there any way to do this efficiently.
>>
>
> You could use a MatNest, however now this seems like thw wrong way to
> calculate it. Why
> do you want to put a matrix polynomial into another matrix?
>
>    Matt
>
>
>> On Tue, Aug 4, 2015 at 5:45 PM, Patrick Sanan <patrick.sanan at gmail.com>
>> wrote:
>>
>>> On Tue, Aug 04, 2015 at 03:42:14PM +0900, Cong Li wrote:
>>> > Thanks for your reply.
>>> >
>>> > I have an other question.
>>> > I want to do SPMM several times and combine result matrices into one
>>> bigger
>>> > matrix.
>>> > for example
>>> > I firstly calculate AX1=B1, AX2=B2 ...
>>> > then I want to combine B1, B2.. to get a C, where C=[B1,B2...]
>>> >
>>> > Could you please suggest a way of how to do this.
>>> This is just linear algebra, nothing to do with PETSc specifically.
>>> A * [X1, X2, ... ] = [AX1, AX2, ...]
>>> >
>>> > Thanks
>>> >
>>> > Cong Li
>>> >
>>> > On Tue, Aug 4, 2015 at 3:27 PM, Jed Brown <jed at jedbrown.org> wrote:
>>> >
>>> > > Cong Li <solvercorleone at gmail.com> writes:
>>> > >
>>> > > > Hello,
>>> > > >
>>> > > > I am a PhD student using PETsc for my research.
>>> > > > I am wondering if there is a way to implement SPMM (Sparse
>>> matrix-matrix
>>> > > > multiplication) by using PETSc.
>>> > >
>>> > >
>>> > >
>>> http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/MatMatMult.html
>>> > >
>>>
>>
>>
>
>
> --
> What most experimenters take for granted before they begin their
> experiments is infinitely more interesting than any results to which their
> experiments lead.
> -- Norbert Wiener
>
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