On Thu, Jun 30, 2011 at 5:11 PM, Barry Smith <bsmith at mcs.anl.gov> wrote: > > On Jun 29, 2011, at 10:35 PM, John Fettig wrote: > >> On Wed, Jun 29, 2011 at 11:21 PM, Barry Smith <bsmith at mcs.anl.gov> wrote: >>> ?If you pass in SAME_PRECONDITIONER to the KSPSetOperators() it is simply >>> impossible that it will rebuild the preconditioner. There must be another >>> explanation as to what is going on. Are you calling anything else on the >>> KSP? >> >> You are right. ?I was playing around with options and had set it to >> SAME_NONZERO_PATTERN for the first iteration at each timestep to make >> sure that would work (it does), and forgot to change it back. >> >> When it is actually set to SAME_PRECONDITIONER and I duplicate Amat to >> Pmat and pass them to KSPSetOperators() before every KSPSolve, it >> definitely uses the same preconditioner (as reported by -info), but >> unfortunately it reverts back to the behavior I saw previously. > > ? What do you mean? Reverts back to? After some iterations? Copying the > matrix and passing it into KSPSetOperators() as the Pmat cannot make any > difference.
I mean that it doesn't make any difference, as you expect. > ? Can you send us a code that reproduces the problem you think is happening > (petsc-maint at mcs.anl.gov), I cannot get a consistent handle on the issue. I will see what I can do. John
