[petsc-users] Matrix dot product

[David Gross]

Hi Matt,
I took a deeper look into the dev documentation and the src/mat code. From
what I understand there are multiple places that the code needs to be added
or referenced in. I created a copy of AXPY in axpy.c and compiled without
issue and could even reference it in my code without compiler error, but
found that it wasn't actually doing anything as best I can tell. Am I
correct in that one must make implementations for each matrix type in
mat/impls? Also I assume that it needs to be added to matipl.h,
include/petscmat.h, and  finclude/petscmat.h .

Is there somewhere that documents the process of adding functions to PETSc
classes? I couldn't find anything in the developers manual.

Regards,
Dave

On Thu, Sep 14, 2017 at 10:07 PM, David Gross <davegwebb10 at gmail.com> wrote:

> Hi Matt,
> Noted for the naming convention.
>
> Yes, it is a Newton method (see Pan, V. and Reif, J., Fast and Efficient
> Parallel Solution of Dense Linear Systems, Computers Math. Applications.
> Vol. 17, No. 11, pp. 1481-1491, 1989)
>
> The dense matrix I have is repeatedly inverted while slowly changing such
> that the previous inverse is a near perfect guess for the new inverse.
>
> Regards,
> Dave
>
> On Thu, Sep 14, 2017 at 2:49 AM, Matthew Knepley <knepley at gmail.com>
> wrote:
>
>> On Wed, Sep 13, 2017 at 6:14 PM, David Gross <davegwebb10 at gmail.com>
>> wrote:
>>
>>> Hi Matt,
>>> Thank you for getting back to me. Your answer confirms what I thought in
>>> terms of existing functionality. I think it shouldn't be too hard to make a
>>> copy of MatAXPY to MatAXY where it performs Xij = A*Xij*Yij (or without the
>>> A). I could then do the MatNorm of the resulting matrix to get what I need.
>>>
>>> Is a MatAXY function desirable as a source contribution?
>>>
>>
>> Yes. I would prefer calling it MatPointwiseMult, since you can see it as
>> VecPointwiseMult on a Vec obtained
>> from forgetting the linear operator structure of the matrix (forgetful
>> functor).
>>
>>
>>> I am hoping to use PETSc for performing basic vector and matrix
>>> operations on dense matrices and 1D vectors. The main uses are matmult,
>>> matmatmult and matrix additions and scaling. The application is for
>>> implementing a parallel version on an existing Pan-Reif matrix inversion
>>> algorithm.
>>>
>>
>> Is this Newton's method on the vector space of matrices?
>>
>>   Thanks,
>>
>>     Matt
>>
>>
>>> The choice of using PETSc is mostly due to us already using it in the
>>> same program to solve sparse matrices (with MUMPS) with the goal of
>>> avoiding adding yet another package (ex ScaLAPACK/PBLAS) into the code even
>>> if other packages may be more directly oriented towards my application.
>>>
>>> Regards,
>>> Dave
>>>
>>>
>>>
>>> On Mon, Sep 11, 2017 at 2:19 AM, Matthew Knepley <knepley at gmail.com>
>>> wrote:
>>>
>>>> On Sun, Sep 10, 2017 at 5:51 PM, David Gross <davegwebb10 at gmail.com>
>>>> wrote:
>>>>
>>>>> Hello,
>>>>> I was wondering if there was a matrix equivalent to the vecDot
>>>>> function (Frobenius inner product)? As far as I can tell the closest thing
>>>>> is MatNorm with NORM_FROBENIUS, but obviously this is acting on only one
>>>>> matrix.
>>>>>
>>>>> If there is not a built in function, what is the best way to compute
>>>>> this? I am working fortran90.
>>>>>
>>>>
>>>> We do not have this. However, it would be trivial to add since we have
>>>>
>>>>   http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpage
>>>> s/Mat/MatAXPY.html
>>>>
>>>> since you just replace + with * in our code. You could argue that we
>>>> should have written for
>>>> a general ring, but C makes this cumbersome. Do you think you could
>>>> make the change?
>>>>
>>>> What are you using this for?
>>>>
>>>>   Thanks,
>>>>
>>>>      Matt
>>>>
>>>>
>>>>> Regards,
>>>>> Dave
>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> 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
>>>>
>>>> http://www.caam.rice.edu/~mk51/
>>>>
>>>
>>>
>>
>>
>> --
>> 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
>>
>> http://www.caam.rice.edu/~mk51/
>>
>
>
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