[petsc-users] solving Ax=b with constant A

[likunt at caltech.edu]

Dear Petsc developers,

I am solving a linear system Ax=b, while A is constant and b is changing
in each time step. Here is the code I wrote:

/****************************************************************
...compute matrix A...
KSPCreate(PETSC_COMM_WORLD, &ksp);  CHKERRQ(ierr);
KSPSetOperators(ksp, A, A, SAME_PRECONDITIONER);  CHKERRQ(ierr);
KSPSetTolerances(ksp, 1.e-5, 1.E-50, PETSC_DEFAULT, PETSC_DEFAULT);
KSPSetFromOptions(ksp);
for(int step=0; step<STEP; step++)
{
    ... compute vector b ...
    KSPSolve(ksp, b, x);
}
*****************************************************************/

I tested a system with size 1725*1725, on 4 processors, it takes 0.06s.
Would you please let me know if there is a way to improve its efficiency?
Thanks.