James, My understanding is that you call MatMatMult in sequential for computing C = A*B, in which A is in aij format, and B is dense, and the product C is dense, but gives different values than what you got from Matlab.
Do you have a stand-alone petsc code to reproduce this so I can investigate what goes wrong? Hong On Sun, Apr 5, 2015 at 3:44 PM, Barry Smith <[email protected]> wrote: > > We would need to see the PETSc side of the code to see if there is > anything wrong there. > > > On Apr 5, 2015, at 3:35 PM, James A Charles <[email protected]> wrote: > > > > Hi Hong, > > > > You can open up matmatmult_comparison.mat in MATLAB ( load > matmatmult_comparison.mat ). That .mat contains A, B, C, and C_MATLAB. I > called matmatmult in sequential. We use AIJ when A2 was sparse but at the > time of this multiplication everything was dense. > > > > Thanks, > > James > > > > > > ----- Original Message ----- > > From: "Hong" <[email protected]> > > To: "James A Charles" <[email protected]> > > Cc: "PETSc users list" <[email protected]>, [email protected], > "Daniel Mejia" <[email protected]>, "Tillmann Kubis" <[email protected]> > > Sent: Sunday, April 5, 2015 4:25:39 PM > > Subject: Re: [petsc-users] MatMatMult with dense matrices. > > > > > > > > > > James: > > > > > > I'm multiplying two dense matrices. I compared the results against > MATLAB and I am getting different results. Attached you will see a zip that > contains a .mat file that has the A, B, and C. C_MATLAB is the > multiplication of A*B in MATLAB and C is the PETSc 3.4.3 result. I also > attached the .m files A, B, and C that were saved from PETSc. Is there > something I'm doing wrong or > > > > > > What is the file type of matmatmult_comparison.mat? > > How to read it? > > I need to see how it defers from C.m. > > > > > > > > any reason due to the shape of the matrices that this would fail? If it > gives any more information we convert the previous matrix that A is formed > of A2 (A = A1*A2) to dense prior to the multiplication using MatConvert. > > > > > > > > It seems both A and B are dense, complex square matrices. > > Did you call MatMatMult() in sequential or parallel? What matrix format > did you use? > > > > > > Hong > >
