On Tuesday March 22 2011 03:31:18 Christian Clason wrote:
> Question #149919 on DOLFIN changed:
> https://answers.launchpad.net/dolfin/+question/149919
>
> Christian Clason posted a new comment:
> Just a small update: The problem seems to be indeed with
> PETScKrylovSolver, since PETScKrylovMatrix by itself works fine even
> with standard vectors:
>
> 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,args[0])
> f = du*v*dx
> problem = VariationalProblem(a, f, bc)
> dy = problem.solve()
> args[1][:] = dy.vector()[:]
>
> H = NewtonMatrix()
>
> y = Function(V)
> b = project(Constant(1.0),V)
>
> H.mult(b.vector(),y.vector())
This is expected to work, as everything is handled in Python. But when you use
the KrylovSolver we take a detour through C++. Your python mult function is
actually called from within C++, through a tricky callback machinery that SWIG
provides.
> print(y.vector().norm('l2'))
>
> However,
>
> NewtonSolver = PETScKrylovSolver('cg', 'none')
> NewtonSolver.solve(H, b.vector(), y.vector())
>
> throws the error
>
> TypeError: in method 'PETScKrylovSolver_solve', argument 3 of type
> 'dolfin::PETScVector &'
That is because the solve method that takes a PETScKrylovMatrix as first
argument needs a PETScVector and not a GenericVector as you provides above.
I really suspect that this is related to shared_ptr. I do not think the
shared_ptr functionality provides dereference typemaps for shared_ptr vectors.
It might be worth adding a shared_ptr version of all calls in
PETScKrylov{Matrix, Solve}.
Christian could you link to this thread when you file the bug report?
Johan
> Christian
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