ouuuuu, this might be the lucky guess, i wasn't aware of that... Ostien, Jakob T wrote: > In a totally blind guess, I believe that for a nonlinear problem, the linear > form used to require a minus sign (DOLFIN 0.8), but now (DOLFIN 0.9+) the > minus sign is built into NewtonSolver. You might want to check that first. > > Jake > > > On 5/1/09 3:09 AM, "Patrick Riesen" <[email protected]> wrote: > >> hello! >> >> i want to update my powerlaw solver from dolfin 0.8 to dolfin 0.9.2. >> the solver class is derived from the NonlinearProblem class and i >> followed the CahnHillard-demo to do something similar for updating from >> 0.8 to 0.9.2. >> >> However I have a problem which i do not understand: >> >> If i hand the created forms to VariationalProblem and let it solve, all >> works fine and in the second iteration the newton solver converges (if i >> initialize a newtonian problem just for checking). >> >> if i do >> >> newtonsolver.solve(*this,uu->vector()); >> >> the problem gets solved as well, i.e. all bcs and my own void F and void >> J get called but it does not converge, it's like the problem gets solved >> over and over again and the solution is added, because in the end i get >> a solution but it's the number of iterations \times velocity. >> >> i tried all kinds of things (with/without pointers, no cast/cast, >> different classes for problem/solve ...) but i don't get it, i miss >> something. >> >> maybe somebody has a hint or does see my error and can help me turn on >> the light? >> >> many thanks in advance >> >> patrick >> >> >> below is a code snippet of the main part: >> /----------------------------------------------------------------------------- >> -- >> _uu = new Function(*_V); >> Function* __uu = dynamic_cast<Function*>(_uu); >> >> // create the forms >> a_powstokes = new PowerlawStokesBilinearForm(*_V,*_V); >> PowerlawStokesBilinearForm* _a_powstokes = >> dynamic_cast<PowerlawStokesBilinearForm*>(a_powstokes); >> _a_powstokes->w0 = *__uu; >> _a_powstokes->eta1 = eta; >> _a_powstokes->eta2 = d_eta; >> >> >> L_powstokes = new PowerlawStokesLinearForm(*_V); >> PowerlawStokesLinearForm* _L_powstokes = >> dynamic_cast<PowerlawStokesLinearForm*>(L_powstokes); >> _L_powstokes->w0 = *__uu; >> _L_powstokes->eta1 = eta; >> _L_powstokes->f = f; >> >> // VariationalProblem pde(*a_powstokes, *L_powstokes, bcs, true); >> // pde.solve(fluid.velocity(),fluid.pressure()); >> >> newtonsolver.solve(*this,__uu->vector()); >> _______________________________________________ >> 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
