On Sun, Jun 10, 2012 at 5:42 PM, TAY wee-beng <zonexo at gmail.com> wrote:
> Hi, > > Currently, my matrix A changes its non zero position at each time step. > > For e.g.: At a particular node, at time step = 1, I will insert values > into its east, west neighbours. At time step = 2, I will insert values > into its east, north neighbours. Hence, the non-zero positions at each row > will be different at each time step. However, the max values per row will > always be 5 or less. > > Currently, after MatSetValues and MatAssemblyBegin/End, I call: > > *call MatSetOption(A_mat,MAT_NEW_NONZERO_LOCATIONS,PETSC_TRUE,ierr) > > call KSPSetOperators(ksp,A_mat,A_mat,DIFFERENT_NONZERO_PATTERN,ierr) > > call KSPGetPC(ksp,pc,ierr) > > ksptype=KSPBCGS > > call KSPSetType(ksp,ksptype,ierr) > > call KSPSetFromOptions(ksp,ierr) > > call KSPSolve(ksp,b_rhs,xx,ierr)* > > Is this sufficient and correct? If so, apart from KSPSolve, MatSetValues > and MatAssemblyBegin/End, can I only call the other subroutines once at the > 1st time step? > > Or do I have to explicitly destroy the matrix and create a new one? I > think I ask this question a while ago but I can't find the email now. > After assembly the nonzero pattern is fixed. The right thing to do is put in explicit zeros for the rest of the stencil. Matt > > -- > Yours sincerely, > > TAY wee-beng > > -- 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/20120610/587b42ff/attachment.html>
