John Mousel <[email protected]> writes:

> I'm trying to reuse the PC constructed by GAMG during a sub-iterative
> procedure where KSPSolve is called with the same matrix repeatedly. The
> right-hand side changes during the sub-iteration. I've been attempting to
> use SAME_PRECONDITIONER for nit = 2..., 

What do you mean by SAME_PRECONDITIONER?  If you are solving with the
same matrix, you can just call KSPSolve without KSPSetOperators.

> Is there a dependence on the right-hand side in GAMG somewhere?

It uses a pseudo-random number generator for eigenvalue estimation.  Try
adding

  -random_seed 1

to your run and see if it cuts the variation you see.

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