Use -ksp_type gmres to get it to print the residuals. With preonly it doesn't compute or print them.
> On Jul 15, 2016, at 11:28 AM, Hoang Giang Bui <[email protected]> wrote: > > I used > > -ksp_monitor_true_residual > -ksp_monitor_true_solution > -ksp_converged_reason > > with MUMPS but it does not compute the true residual. Should I compute that > myself? > > Below is a sample for a full log of MUMPS > https://www.dropbox.com/s/fy5uknooxw77r19/log13Jun16_mumps?dl=0 > > > Giang > > On Fri, Jul 15, 2016 at 2:52 AM, Mark Adams <[email protected]> wrote: > > > 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 > >
