[petsc-users] Solution Diverging

Matthew Knepley knepley at gmail.com
Fri Apr 5 20:05:07 CDT 2019

On Fri, Apr 5, 2019 at 4:33 PM Maahi Talukder via petsc-users <
petsc-users at mcs.anl.gov> wrote:

> Dear All,
> I am solving a linear system arising from 9-point discretization of
> Poisson equation to generate grid. KSP solvers are giving nice converged
> result when I am dealing with a large matrix. But when I am trying to
> implement KSP solvers when the matrix is smaller and the values are smaller
> too, the solution is diverging.
> Any suggestions how to get around this problem?

For any solver question, send us the output from

  -ksp_view -ksp_monitor_true_residual -ksp_converged_reason

Divergence is surprising since the default Krylov solver (GMRES) cannot



> Regards,
> Maahi Talukder

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

https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
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