[petsc-users] use kspsolve repeately

[Matthew Knepley]

On Sat, Aug 24, 2013 at 4:57 AM, 丁老师 <ztdepyahoo at 163.com> wrote:

> in  my code, i need to use kspsolve in the following way
>
>     KSP ksp;
>
>     KSPCreate(PETSC_COMM_WORLD,&ksp);
>     KSPSetOperators(ksp,A,A,SAME_NONZERO_PATTERN);
>     KSPSetOperators(ksp,A,A,SAME_PRECONDITIONER);
>     KSPSetInitialGuessNonzero(ksp,PETSC_TRUE)
>      KSPSetType(ksp,KSPBCGS);
>     KSPSetFromOptions(ksp);
>
>   set the matrix A value and right hand side bu and bv.
>     kspsolve(A,bu);
>     kspsolve(A,bv);
>   change the value of matrix A and bu bv,
>      kspsolve(A,bu);
>      kspsolve(A,bv);
>
>  the first and second call to the kspsolve use the same preconditioner.
> but which preconditoner does the third and fourth call to the kspsolve
> since the value of the matrix A has changed.
>

The first call is redundant, and the subsequent solves use the same
preconditioner, as you asked.

   Matt


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-- 
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
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