On Fri, Mar 24, 2017 at 8:56 AM, alexandre this <[email protected]> wrote:
> Dear all, > > I'm in the configuration where I need to solve a linear system Ax = b > where b is very small although not equal to zero. > > It appears that, in this configuration, the initial residual of the first > iteration of the solver is completely out of reach and the > KSP_DIVERGED_DTOL is raised. > For any convergence question, we need the output from -ksp_monitor_true_residual -ksp_converged_reason -ksp_view > In particular, when using the "-ksp_monitor_true_residual flag", I get the > following : > 0 KSP preconditioned resid norm 2.907111674781e+00 true resid norm > 1.955854211540e+02 ||r(i)||/||b|| 1.765818923254e+09 > We need to see the error, not just the first line. You can always raise the tolerance, but divergence means that the norm is increasing. Matt > What is the best course of action in this case ? > > Best, > Alexandre > > > -- > Alexandre This > > Doctorant CIFRE (Philips Healthcare - INRIA) : Fusion Image / Modèles > Numériques pour la quantification de la sévérité de la régurgitation m > itrale > > Master 2 Recherche Mathématiques, Vision, Apprentissage - ENS Cachan > Ingénieur spécialisation Santé&Technologie - ECE Paris > Bachelor of Science : Informatics - Aalborg University, Danemark > > tel : 06.32.57.12.44 > -- 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
