Question #108259 on DOLFIN changed: https://answers.launchpad.net/dolfin/+question/108259
Murtazo Nazarov posted a new comment: Anders Logg wrote: > Question #108259 on DOLFIN changed: > https://answers.launchpad.net/dolfin/+question/108259 > > Anders Logg posted a new comment: > On Thu, Apr 29, 2010 at 04:14:21PM -0000, Murtazo Nazarov wrote: > >> Question #108259 on DOLFIN changed: >> https://answers.launchpad.net/dolfin/+question/108259 >> >> Status: Answered => Solved >> >> Murtazo Nazarov confirmed that the question is solved: >> Yes, it seems hypre in my solver does not converge only in the first >> iteration. Before it was just a warning, but with the latest dolfin it >> stoped since it is assumed that it is an error. >> >> Here I made a test for the same problem using the following lines: >> >> solver = KrylovSolver("gmres") >> solver.parameters["monitor_convergence"] = True >> solver.parameters["error_on_nonconvergence"] = False >> .. >> >> "Old" dolfin gives: >> .... >> Applying boundary conditions to linear system. >> Applying boundary conditions to linear system. >> Solving linear system of size 4184 x 4184 (PETSc Krylov solver). >> 0 KSP preconditioned resid norm 2.663347782311e+02 true resid norm >> 1.371810197831e+01 ||Ae||/||Ax|| 7.817835153984e+08 >> *** Warning: Krylov solver did not converge (PETSc reason -4). >> PETSc Krylov solver (gmres, hypre) failed to converge in 0 iterations. >> ... >> >> and the latest dolfin gives: >> >> Applying boundary conditions to linear system. >> Applying boundary conditions to linear system. >> Solving linear system of size 4184 x 4184 (PETSc Krylov solver). >> 0 KSP preconditioned resid norm 6.346755394553e+02 true resid norm >> 3.269022479529e+01 ||Ae||/||Ax|| 3.675021072956e+08 >> *** Warning: Krylov solver did not converge (PETSc reason -4). >> PETSc Krylov solver (gmres, hypre) failed to converge in 0 iterations. >> >> It happened because of the luck of stabilization in startup. >> >> It is nice to know about the latest flags in the parameter list for the >> Krylov solver. >> >> murtazo >> > > ok, good to know. So there is nothing wrong with the solver. > > I suggest you let "error_on_nonconvergence" stay true, otherwise you > will not see when it fails. > > -- > Anders > > yes, you are right. I put it false only for the first time-step, then I change it to be true. Otherwise I still get warning, which I usually track. murtazo -- You received this question notification because you are a member of DOLFIN Team, which is an answer contact for DOLFIN. _______________________________________________ Mailing list: https://launchpad.net/~dolfin Post to : [email protected] Unsubscribe : https://launchpad.net/~dolfin More help : https://help.launchpad.net/ListHelp
