You can use KSPBuildResidual(). Matt
On Mon, Sep 21, 2009 at 12:44 PM, Ryan Yan <vyan2000 at gmail.com> wrote: > Hi All, > The following question is only for test and comparison reason. > > Is there a command line option to set up using 1-Norm(sum of absolute value > of residuals) as convergence monitor and test. > > Alternatively, if I can get the residual "r" out at the end of each > iteration, then it is going to be much simpler, since I can just call > VecNorm(r, NORM_1, &r_ell1) and pass the r_ell1 into the convergence monitor > and test. Can anyone inform me if PETSc has an interface for the resuidual > r? > > Or one has to call the convergence test: > MyKSPConverged(ksp,n,rnorm,flag,dummy); > and following the steps: > 1. fetch the exact solution: > > KSPBuildSolution(ksp,PETSC_NULL_OBJECT,x,ierr) > > 2. calculate the residual: > > pass the Right Hand side and the Matrix in to calculate the 1-Norm. But > this step is *not* obvious, since the matrix and rhs is already distributed > over each processes. > > 3. set up the convergence test based on the 1_Norm residual. > > > Thank you very much, > > > Yan > -- 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/20090921/1a535518/attachment.htm>
