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

[Pierre Jolivet]

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 <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> 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> on behalf of Barry Smith <bsmith at petsc.dev>
> Sent: Thursday, July 14, 2022 4:38 PM
> To: Pierre Jolivet <pierre at joliv.et>
> Cc: For users of the development version of PETSc <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> 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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