[petsc-users] no decrease in iteration counts of KSPCG during time stepping

[Alp Kalpalp]

Hi,

I implemented a newmark time stepping algorithm without using TS structure.
I am following ex59 about PCBDDC.

ComputeMatrix
ComputeKSPBDDC

for // a time loop
{
Compute RHS
KSPSolve
GatherResults
MoveToNextTS
}


However, when I watch the iteration counts of KSPSolve they do not decrease
signicantly..Decrease was around 5%.

So I have some problems;

1-) I guess currently, factorization is not taking place for each time step
in my code. Ok this is expected. But I wonder whether Kspsolve stores the
Krylov subspace vectors and reuse them for the next time step.

2-) PCBDDC uses KSPCG and AFAIK petsc doesnot have preconditioned conjugate
projected gradient (PCPG). Is it possible to simulate PCPG iteration in
some way?

Thanks,
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