[petsc-dev] MatProduct_AtB --with-scalar-type=complex

[Zhang, Hong]

Pierre,
I believe you are in the correct direction for debugging MatProductReplaceMats() . I 'll investigate it and let you know the result.
Hong

________________________________
From: Pierre Jolivet <pierre at joliv.et>
Sent: Friday, July 15, 2022 12:01 AM
To: Zhang, Hong <hzhang at mcs.anl.gov>
Cc: Barry Smith <bsmith at petsc.dev>; For users of the development version of PETSc <petsc-dev at mcs.anl.gov>
Subject: Re: [petsc-dev] MatProduct_AtB --with-scalar-type=complex

Barry,
MatTransposeMatMultSymbolic_SeqAIJ_SeqAIJ() is indeed called.
product->alg is default, square is PETSC_FALSE.

Hong,
I believe the issue comes from the fact that atb->updateAt is PETSC_FALSE in MatProductNumeric_AtB_SeqAIJ_SeqAIJ().
If the name of this variable is relevant to its purpose, I believe it should be set to PETSC_TRUE when calling MatProductReplaceMats() whenever A is changed.
I would prefer using MatProductReplaceMats() because I’m implementing the same MatConvert() as MatNormal for the Hermitian case and it’s the only way to reuse the symbolic product, cf. https://petsc.org/main/src/mat/impls/normal/normm.c.html#line315 in the case where --with-scalar-type=real

Thanks,
Pierre

On 15 Jul 2022, at 5:52 AM, Zhang, Hong <hzhang at mcs.anl.gov<mailto:hzhang at mcs.anl.gov>> wrote:

Pierre,
Our MatProductReplaceMats() is not well tested, which might be buggy. I simplified your code without calling MatProductReplaceMats() and got correct results in the cases
./ex1111 -product_view ::ascii_matlab -convert false/true -correct false
and
./ex1111 -product_view ::ascii_matlab -convert false/true -correct true

My code is attached. I'll investigate MatProductReplaceMats().
Hong




________________________________
From: petsc-dev <petsc-dev-bounces at mcs.anl.gov<mailto:petsc-dev-bounces at mcs.anl.gov>> on behalf of Barry Smith <bsmith at petsc.dev<mailto:bsmith at petsc.dev>>
Sent: Thursday, July 14, 2022 4:38 PM
To: Pierre Jolivet <pierre at joliv.et<mailto:pierre at joliv.et>>
Cc: For users of the development version of PETSc <petsc-dev at mcs.anl.gov<mailto:petsc-dev at mcs.anl.gov>>
Subject: Re: [petsc-dev] MatProduct_AtB --with-scalar-type=complex


  Can you confirm if MatTransposeMatMultSymbolic_SeqAIJ_SeqAIJ() ends up being called for you and what path it takes inside that routine (depends) on the algorithm it is using.



> On Jul 14, 2022, at 4:30 PM, Pierre Jolivet <pierre at joliv.et<mailto:pierre at joliv.et>> wrote:
>
> Hello,
> In the following example, the SeqAIJ implementation of MatProduct_AtB produce a different (and wrong) result, compared to the SeqDense implementation or MATLAB.
> I want to compute B = A^H A (where ^H is the Hermitian transpose).
> So I create a MatProduct with A and A.
> Duplicate A into another Mat which I conjugate.
> And I replace the first Mat of the product with this conjugate.
> I expect to get the proper result, which I don’t.
> Is the MatProduct_AtB implementation in the complex case not computing A^T B (where ^T is the transpose)?
> For reference, here is how to properly compute A^H A with current main: conj(A^H conj(A)) — so it requires an extra MatConjugate I’d like to avoid.
>
> Thanks,
> Pierre
>
> <ex1111.c>
>
> $ ./ex1111 -product_view ::ascii_matlab -A_view ::ascii_matlab -convert false
> %Mat Object: 1 MPI process
> %  type: seqdense
> % Size = 2 2
> Mat_0xc4000001_0 = zeros(2,2);
> Mat_0xc4000001_0 = [
> 7.2003197397953400e-01 + 6.1793966542126100e-02i 3.9777780919128602e-01 + 7.3036588248200474e-02i
> 1.0022337819588500e-02 + 1.4463931936456476e-01i 1.0386628927366459e-01 + 2.5078039364333193e-01i
> ];
> %Mat Object: 1 MPI process
> %  type: seqdense
> % Size = 2 2
> Mat_0xc4000001_1 = zeros(2,2);
> Mat_0xc4000001_1 = [
> 5.4328551781548817e-01 + 0.0000000000000000e+00i 3.2823965013353340e-01 + 1.5498666614872689e-02i
> 3.2823965013353340e-01 + -1.5498666614872689e-02i 2.3724054059134142e-01 + 0.0000000000000000e+00i
> ];
>
> $ ./ex1111 -product_view ::ascii_matlab -convert true
> %Mat Object: 1 MPI process
> %  type: seqaij
> % Size = 2 2
> % Nonzeros = 4
> zzz = zeros(4,4);
> zzz = [
> 1 1  4.9380746380098023e-01 9.1886511660038694e-02
> 1 2  2.4666779825931440e-01 9.4705502650537468e-02
> 2 1  2.4666779825931440e-01 9.4705502650537468e-02
> 2 2  1.0079024247365802e-01 1.1019992594899400e-01
> ];
> Mat_0xc4000001_0 = spconvert(zzz);
>
> $ ./ex1111 -product_view ::ascii_matlab -convert true -correct true
> %Mat Object: 1 MPI process
> %  type: seqaij
> % Size = 2 2
> % Nonzeros = 4
> zzz = zeros(4,4);
> zzz = [
> 1 1  5.4328551781548828e-01 -0.0000000000000000e+00
> 1 2  3.2823965013353340e-01 1.5498666614872696e-02
> 2 1  3.2823965013353340e-01 -1.5498666614872696e-02
> 2 2  2.3724054059134142e-01 -0.0000000000000000e+00
> ];
> Mat_0xc4000001_0 = spconvert(zzz);
>
> <Screenshot 2022-07-14 at 10.12.53 PM.png>

<ex1111.c>

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