[petsc-users] MatStructure flag in KSPSetOperators

[Kuhlemann, Verena]

Hi,

I am not sure that I understand the MatStructure flag in the call of KSPSetOperators
correctly.

If I use KSPSetOperators(ksp, A, P, DIFFERENT_NONZERO_PATTERN) and then
solve two linear systems with the same matrix operators but different rhs is
the preconditioner reassembled in every solve. I.e., if I call
KSPSolve(ksp,b1,x1);
KSPSolve(ksp,b2,x2);

And if I use KSPSetOperators(ksp, A, P, SAME_PRECONDITIONER) the preconditioner is
only setup one time and reused later.

Or is the flag only important if I change the matrix operators in between.

Thank you,
Verena


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