Thanks. It is very useful. Xiaodong Liu, PhD X: Computational Physics Division Los Alamos National Laboratory P.O. Box 1663, Los Alamos, NM 87544 505-709-0534
On Tue, Mar 17, 2020 at 8:17 AM Matthew Knepley <[email protected]> wrote: > On Mon, Mar 16, 2020 at 4:32 PM Xiaodong Liu <[email protected]> wrote: > >> Hi, all, >> >> I am testing KSPSetInitialGuessNonzero using the case >> >> >> https://www.mcs.anl.gov/petsc/petsc-current/src/ksp/ksp/examples/tutorials/ex50.c.html >> >> This case is special. WIth zero initial guess, 1 iteration can deliver >> the exact solution. But when I tried true for KSPSetInitialGuessNonzero, it >> shows the same convergence history as false. >> >> Does the code change KSPSetInitialGuessNonzero to false automatically? >> > > For that flag to make any difference, you have to pass in a nonzero vector > to KSPSolve(). This example does not do that. > Were you doing that? > > Thanks, > > Matt > > >> Take care. >> >> Thanks, >> >> Xiaodong Liu, PhD >> X: Computational Physics Division >> Los Alamos National Laboratory >> P.O. Box 1663, >> Los Alamos, NM 87544 >> 505-709-0534 >> > > > -- > 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 > > https://www.cse.buffalo.edu/~knepley/ > <http://www.cse.buffalo.edu/~knepley/> >
