<html><head><meta http-equiv="Content-Type" content="text/html; charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div class=""><br class=""></div><div class=""> Giovane,</div><div class=""><br class=""></div><div class=""> Thanks for the complete report. It looks like we may be missing a check in our FGMRES implementation that allows the iteration to continue after a NaN/Inf. </div><div class=""><br class=""></div><div class=""> I will explain how we handle the checking and then attach a patch that you can apply to see if it resolves the problem. Whenever our KSP solvers compute a norm we</div><div class="">check after that calculation to verify that the norm is not an Inf or Nan. This is an inexpensive global check across all MPI ranks because immediately after the norm computation all ranks that share the KSP have the same value. If the norm is a Inf or Nan we "short-circuit" the KSP solve and return immediately with an appropriate not converged code. A quick eye-ball inspection of the FGMRES code found a missing check. </div><div class=""><br class=""></div><div class=""> You can apply the attached patch file in the PETSC_DIR with </div><div class=""><br class=""></div><div class="">patch -p1 < fgmres.patch</div><div class="">make libs</div><div class=""><br class=""></div><div class="">then rerun your code and see if it now handles the Inf/NaN correctly. If so we'll patch our release branch with the fix.</div></body></html>