On Thu, Jul 14, 2016 at 7:29 PM, Matthew Knepley <[email protected]> wrote:
> On Thu, Jul 14, 2016 at 6:27 PM, Mark Adams <[email protected]> wrote: > >> >>> >>> Notice that there are 7 orders of magnitude between the apparent >>> residual (using the preconditioner), and the actual residual, Ax - b. >>> You are using Hypre, and this generally means the Hypre coarse grid >>> operator is crap. Please >>> >>> >> Huh?, this data looks fine, both the true and preconditioned residual >> stay separated by about 9 orders of magnitude. This just tells you that the >> norm of A (or is it A^-1) is 10^9. Am I misunderstanding this? >> > > This is why Barry and I asked for a comparsion with MUMPS. If you are > right, and its just the condition number, > I said norm not condition number. I trust I'm missing something in this thread. > the LU > will not be any more accurate. > > Matt > > -- > What most experimenters take for granted before they begin their > experiments is infinitely more interesting than any results to which their > experiments lead. > -- Norbert Wiener >
