[petsc-users] Very small right hand side and KSP_DIVERGED_DTOL

[alexandre this]

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.

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

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 mitrale

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
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