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[Christian Clason <question149919@xxxxxxxxxxxxxxxxxxxxx>]

Question #149919 on DOLFIN changed:
https://answers.launchpad.net/dolfin/+question/149919

    Status: Answered => Open

Christian Clason is still having a problem:
Yes, via PETScKrylovSolver. Below is a minimal example for what I'm
trying to do.

Christian

from dolfin import *

def boundary(x,on_boundary):
    return on_boundary

mesh = UnitSquare(32, 32)
V = FunctionSpace(mesh, 'CG', 1)

u0 = Constant(0.0)
bc = DirichletBC(V, u0, boundary)
u = TrialFunction(V)
v = TestFunction(V)
a = inner(grad(u), grad(v))*dx

class NewtonMatrix(PETScKrylovMatrix) :
    def __init__(self) :
        PETScKrylovMatrix.__init__(self, V.dim(), V.dim())

    def mult(self, *args) :  
        du = Function(V)
        du.vector()[:] = args[0][:]
        f = du*v*dx
        problem = VariationalProblem(a, L, bc)
        dy = problem.solve()
        args[1][:] = dy.vector()[:]

H = NewtonMatrix()

E = project(Constant('1'),V)
b = PETScVector(E.vector().size())
b.set_local(E.vector().array())

x = PETScVector(E.vector().size())
x.zero()
NewtonSolver = PETScKrylovSolver('cg', 'none');
NewtonSolver.solve(H, x, b);

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