[petsc-dev] Bug in MatMatMultTranspose for sequantial AIJ matrices from petsc-dev?

[Hong Zhang]

Stefano:

MatMatMultTranspose() has been renamed. With latest petsc-dev:

MatTransposeMatMult - Performs Matrix-Matrix Multiplication C=A^T*B.
MatMatTransposeMult - Performs Matrix-Matrix Multiplication C=A*B^T.

I'm currently working on C=A*B^T. Report to us if you encounter problems.

Hong

> Hi,
>
> I'm using (from error log) "Petsc Development HG revision:
> 0216b5820377f721a70342e04a44fa54f3883ec9  HG Date: Sun Oct 30 23:58:53 2011
> -0500 "
>
> I had some problems using MatMatMultTranspose for SeqAIJ matrices. It seems
> to me that MatMatMultTranspose(A,B,...,MAT_INITIAL_MATRIX,&C), which should
> perform C=A^T*B according to the web pages, doesn't its job. The pseudo-code
> listed below prints
>
> sizes A_II 64 64
> sizes phi D 64 30
> check sizes TM1 30 30
> check sizes TM2 64 64
> check sizes TM3 64 64
> check sizes AUXMAT2 64 30
>
> From the code below, either TM2 and TM3 sizes are wrong. They should be both
> 30 30. It seems that it flips matrices dimensions in creating the output of
> MatMatMultTranspose.
> An inspection of matrix values give me no further insights.
>
> --------------------------------------------------------------------------------------------------------------------
>
>       Mat TM1,TM2,TM3,AUXMAT2;
>       Mat coarse_phi_D;
>
>       .....all matrices involved are Seq_AIJ matrices.............
>
>       ierr = MatGetSize(pcis->A_II,&rows,&columns);
>       printf("sizes A_II %d %d\n",rows,columns);
>       ierr = MatGetSize(coarse_phi_D,&rows,&columns);
>       printf("sizes phi D %d %d\n",rows,columns);
>
>       ierr =
> MatPtAP(pcis->A_II,coarse_phi_D,MAT_INITIAL_MATRIX,1.0,&TM1);
> //TM1=PHI^T*A_II*PHI OK!
>       ierr =
> MatMatMult(pcis->A_II,coarse_phi_D,MAT_INITIAL_MATRIX,1.0,&AUXMAT2);
> //AUXMAT2=A_II*PHI OK!
>       ierr =
> MatMatMultTranspose(coarse_phi_D,AUXMAT2,MAT_INITIAL_MATRIX,1.0,&TM2);
> //TM2=PHI^T*AUXMAT2 WRONG!
>       ierr =
> MatMatMultTranspose(AUXMAT2,coarse_phi_D,MAT_INITIAL_MATRIX,1.0,&TM3);
> //TM3=AUXMAT2^T*PHI WRONG!
>
>       ierr = MatGetSize(TM1,&rows,&columns);
>       printf("check sizes TM1 %d %d\n",rows,columns);
>       ierr = MatGetSize(TM2,&rows,&columns);
>       printf("check sizes TM2 %d %d\n",rows,columns);
>       ierr = MatGetSize(TM3,&rows,&columns);
>       printf("check sizes TM3 %d %d\n",rows,columns);
>       ierr = MatGetSize(AUXMAT2,&rows,&columns);
>       printf("check sizes AUXMAT2 %d %d\n",rows,columns);
>
> ----------------------------------------------------------------------------------------------------------------------------
> --
> Stefano