On Wed, Jan 16, 2013 at 12:09 PM, w_ang_temp <w_ang_temp at 163.com> wrote:
> > > > > > > >At 2012-12-02 23:10:51,"Jed Brown" <jedbrown at mcs.anl.gov> wrote: > > >The test for symmetry is not implemented for all matrix types. Looking at > the code, it seems to only be SeqAIJ, but MatIsTranspose(A,A,...) would > also work >for MPIAIJ. > > > I made a test. I get all the elements of the matrix and compare the > element A(i,j) with > A(j,i). The result shows that the matrix is symmetric. But the result of > MatIsTranspose(A,A,0.0,matsysflg,ierr) > shows that it is unsymmetric(matsysflg=0). I think there is something that > I donot know about using the function. > > Obviously your comparison has a tolerance. Matt > >>On Sun, Dec 2, 2012 at 8:45 AM, w_ang_temp <w_ang_temp at 163.com> wrote: > >> >>Hello, >> >> >> I use MatIsSymmetric to know if the matrix A is symmetric. >> >> >>According to my model, it should be symmetric due to the theory. >> >> >>But I always get the result 'PetscBool *flg = 0', although I >> >> >>set 'tol' a large value(0.001). >> >> >> Because the matrix is of 20000 dimension, I can not output the >> >> >>matrix to the txt. So I want to konw if there is something to be paid >> attention to >> >> >>about the function 'MatIsSymmetric' in version 3.2. Or do I have some >> other ways >> >> >>to determine the symmetry.I think symmetry is one of the most important >> thing >> >> >>in my analysis. >> >> >> Thanks. >> >> >> Jim >> >> >> > > > -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20130116/7e000aae/attachment.html>
