[petsc-users] Speeding-up petsc

[Jed Brown]

Bruno Ramon Batista Fernande <brbfernandes at utexas.edu> writes:

> Hello guys,
>
> I am using petsc is a solver for a finite difference PDE solver.
>
> Basically the coefficient matrix (say A in Ax = b) is well conditioned,
> symmetric, and up to 7 diagonals. Also, no pivoting is necessary for such
> problem and it is always diagonally dominant.
>
> I am using all default options of petsc but I still feel like I could get
> better results by choosing different answers. By default I mean: GMRES
> solver preconditioned on left with ILU(0) and a classical Gram-Schmidt to
> orthogonalize against krylov vector.

You have told us nothing about the performance of this solver.  Always
include -log_summary -ksp_view.

> I am using MAT_STRUCTURALLY_SYMMETRIC option and
> atol = 1.0e-30
> dtol = 1.0e5

Why these options?

How accurate of a solution do you need?
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