Hong, Thanks for explanation. I will try this tomorrow. Good to have this stuff in the help now.
And sorry for misleading you initially. Regards, Alexander ----- Reply message ----- From: "Hong Zhang" <hzh...@mcs.anl.gov> To: "For users of the development version of PETSc" <petsc-dev at mcs.anl.gov> Subject: [petsc-dev] MatMatMult gives different results Date: Tue, Feb 7, 2012 19:09 Alexander : There is something I didn't get yet, I hope you could clarify it. So, when I use flag MAT_INITIAL_MATRIX in test program it works fine. Good to know :-)? If I put this flag in my original program I get dozens of exceptions like: [42]PETSC ERROR: Argument out of range! [42]PETSC ERROR: New nonzero at (1336,153341) caused a malloc! You cannot do??MatCreateMPIAIJ() MatTranspose(A,MAT_INITIAL_MATRIX,&AT); MatCreateMPIAIJ() creates AT and preallocates approximate nonzeros, which does not match exactly the nonzeros in? MatTranspose(A,MAT_INITIAL_MATRIX,&AT);MatTranspose(A,MAT_INITIAL_MATRIX,&AT) creates matrix AT and sets correct nonzero pattern and values in AT.? MatTranspose() only takes in "MAT_INITIAL_MATRIX" - for a new AT, and "MAT_REUSE_MATRIX" when AT is created with?MatTranspose(A,MAT_INITIAL_MATRIX,&AT) and reuse for updating its values (not nonzero patten). I'm updating petsc help menu on?MatTranspose(). Thanks for the report. Hong I changed this flag to MAT_REUSE_MATRIX and exceptions disappeared, but result is incorrect again (same as for MAT_IGNORE_MATRIX)? I tried test program with MAT_REUSE_MATRIX and it also gives different matrix product. Since there is no description of MatReuse structure for MatTranspose it's a bit confusing what to expect from it. Do you mean 'Cm = A'*B;'?? 'Cm = A.'*B;' gives component-wise matrix product, not matrix product. .' operator means non-Hermitian transpose. That is what I get with MatTranspose (in contrast with MatHermitianTranspose) component-wise matrix product would be .* You are correct. Hong? Hong ? C = PetscBinaryRead('C.dat','complex',true); Matrix C is different depending on number of cores I use. My PETSc is: Using Petsc Development HG revision: 876c894d95f4fa6561d0a91310ca914592527960? HG Date: Tue Jan 10 19:27:14 2012 +0100 On 06.02.2012 17:13, Hong Zhang wrote: MatMatMult() in petsc is not well-tested for complex - could be buggy. Can you send us the matrices A and B in petsc binary format for investigation? Hong On Mon, Feb 6, 2012 at 5:55 AM, Alexander Grayver <agrayver at gfz-potsdam.de> wrote: Dear PETSc team, I try to use: call MatMatMult(A,B,MAT_INITIAL_MATRIX,PETSC_DEFAULT_DOUBLE_PRECISION,C,ierr);CHKERRQ(ierr) Where both A and B are rectangular, but A is sparse and B is dense. Both are double complex and distributed. The product PETSc gives me contains some errors in some part of the matrix. I output A, B and C then computed product in matlab. Attached you see figure plotted as: imagesc(log10(abs(C-Cm))) Where Cm -- product computed in matlab. The pattern and amplitude vary depending on the number of cores I use. This picture is obtained for 48 cores (I've tried 12, 64 cores as well). Where should I look for possible explanation? -- Regards, Alexander -- Regards, Alexander -- Regards, Alexander -- Regards, Alexander -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20120207/482f9ee0/attachment.html>