Garth N. Wells wrote: > Nuno David Lopes 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? > > At the moment, yes (note the UMFPACK is an LU solver, so an initial > guess doesn't do anything). > > It's very simple, and I've been meaning to add an option for using an > initial guess. It's also useful for Newton solvers. I'll add something > in the next few days. >
I've added this, although it's untested. Let me know if it works ok. Garth > Garth > > >> 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. >> > > _______________________________________________ > 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
