Sylvain Mercier <[email protected]> writes: > Hello everyone, > > I want to use PCApplyBAorAB symmetrically with a preconditioner from an ICC > factorization. > However, I don't understand why the result is not the same if I use a > natural or a RCM ordering during the factorization.
Uh, ICC is not the same in RCM versus natural ordering. Incomplete factorization is _highly_ order-dependent. > This problem does not occur if I use this routine with PC_LEFT or PC_RIGHT What do you mean "does not occur"? You should expect that changing factorization ordering will always change the preconditioner, though some cases could cancel.
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