Greg : > Yes, they are Hermitian. >
PETSc does not support Cholesky factorization for Hermitian. It seems mumps does not support Hermitian either https://lists.mcs.anl.gov/mailman/htdig/petsc-users/2015-November/027541.html Hong > On Thu, Sep 21, 2017 at 3:43 PM Hong <[email protected]> wrote: > >> Greg: >> >> OK, the difference is whether LU or Cholesky factorization is used. But I >>> would hope that neither one should give incorrect eigenvalues, and when I >>> run with the latter it does! >>> >> Are your matrices symmetric/Hermitian? >> Hong >> >>> >>> On Thu, Sep 21, 2017 at 2:05 PM Hong <[email protected]> wrote: >>> >>>> Gregory : >>>> Use '-eps_view' for both runs to check the algorithms being used. >>>> Hong >>>> >>>> Hi all, >>>>> >>>>> I'm using shift-invert with EPS to solve for eigenvalues. I find that >>>>> if I do only >>>>> >>>>> ... >>>>> ierr = EPSGetST(eps,&st);CHKERRQ(ierr); >>>>> ierr = STSetType(st,STSINVERT);CHKERRQ(ierr); >>>>> ... >>>>> >>>>> in my code I get correct eigenvalues. But if I do >>>>> >>>>> ... >>>>> ierr = EPSGetST(eps,&st);CHKERRQ(ierr); >>>>> ierr = STSetType(st,STSINVERT);CHKERRQ(ierr); >>>>> ierr = STGetKSP(st,&ksp);CHKERRQ(ierr); >>>>> ierr = KSPGetPC(ksp,&pc);CHKERRQ(ierr); >>>>> ierr = KSPSetType(ksp,KSPPREONLY);CHKERRQ(ierr); >>>>> ierr = PCSetType(pc,PCCHOLESKY);CHKERRQ(ierr); >>>>> ... >>>>> >>>>> the eigenvalues found by EPS are completely wrong! Somehow I thought I >>>>> was supposed to do the latter, from the examples etc, but I guess that was >>>>> not correct? I attach the full piece of test code and a test matrix. >>>>> >>>>> Best, >>>>> Greg >>>>> >>>> >>>>
