[petsc-users] ksp/pc nonzero initial guess

[Verena Kuhlemann]

Hello,

I am trying to solve a linear system with GMRES and a preconditioner.
I need a nonzero initial guess and tried to do so by using

         KSPSetInitialGuessNonzero(ksp,PETSC_TRUE);

and       PCSetInitialGuessNonzero(pc,PETSC_TRUE);


Without a preconditioner (setting: PCSetType(pc,PCNONE)) it works and

my nonzero initial guess is used. But if I try to use a preconditioner

the solver always zeroes out the initial guess.


I would greatly appreciate any help.

Thanks,

Verena


Here is the relevant part of my code:

        KSPCreate(PETSC_COMM_WORLD,&ksp);

KSPSetInitialGuessNonzero(ksp,PETSC_TRUE);


KSPSetOperators(ksp,A,A,DIFFERENT_NONZERO_PATTERN);

KSPGetPC(ksp,&pc);

PCSetInitialGuessNonzero(pc,PETSC_TRUE);
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