You can use http://www-unix.mcs.anl.gov/petsc/petsc-as/snapshots/petsc-current/docs/manualpages/KSP/KSPComputeEigenvaluesExplicitly.html
with and without a preconditioner. We have not coded the SVD counterpart, but you can use http://www-unix.mcs.anl.gov/petsc/petsc-as/snapshots/petsc-current/docs/manualpages/KSP/KSPComputeExplicitOperator.html and then call the LAPACK yourself. Matt On Jan 13, 2008 11:23 PM, Yujie <recrusader at gmail.com> wrote: > Hi, everyone > > I want to select iterative methods by observing the singular values > decompostion of the matrix. However, I don't know how to get all the > singular values of the matrix in PETSc. I know the command > "-ksp_monitor_singular_value" may get the max and min singular values at > each iteration. How to get the singular values of the matrix I want to > solve? In addition, when I use the preconditioned iterative method, how to > get the singular values of the preconditioned iterative operator? > > thanks a lot. > > Regards, > Yujie > -- 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
