On Wed, Sep 24, 2008 at 8:36 PM, Nuno David Lopes <[EMAIL PROTECTED]> wrote: > Is there a simple way of setting an initial guess for an Iterative > LinearSolver? > In Umfpack and PETSc the default initial guess is the zero vector right?
Not necessarily: http://www-unix.mcs.anl.gov/petsc/petsc-as/snapshots/petsc-current/docs/manualpages/KSP/KSPSetInitialGuessNonzero.html > For time dependent problems it would be great if one could use the last step > solutions as the initial guess. > I was thinking of something like > ----------------------------------------- > solver.solve(A,x_(n+1),x_n,b) > ----------------------------------------- > where x_n is the initial guess for the iterative solver. > > Also another doubt, (i'm guessing that is my math ignorance only) > is it usual that PETSc::gmres with hypre::amg preconditioner doesn't work. > (After reading that it is so powerfull...) > In a Stokes 566000^2 subsystem it simply blows up with all of the RAM memory > (16Gb). > (I tried it with simpler problems but with bigger systems and it worked > perfectly, converging in <10 iterations.) > > Sorry for some disturbance in the troubled-hard-development times you are > having and thanks again. > > -- > Nuno David Lopes > http://ptmat.ptmat.fc.ul.pt/%7Endl/ > > Wed Sep 24 18:58:27 WEST 2008 > _______________________________________________ > DOLFIN-dev mailing list > [email protected] > http://www.fenics.org/mailman/listinfo/dolfin-dev > _______________________________________________ DOLFIN-dev mailing list [email protected] http://www.fenics.org/mailman/listinfo/dolfin-dev
