dolfin team mailing list archive

[Dag Lindbo <dag@xxxxxxxx>]

Hi all,

The Function class is causing some headaches for me, as I try to
normalize 2-vectors on my mesh. I have a form that defines the
computation of a gradient, so in my solver i have a vactor-values
function, normal_phi (whose components are the gradient vectors at each
vertex). So far it's OK. Now I loop over all vertices and manually
normalize each vector in normal_phi. This works too.

But then the function, normal_phi, goes into a another form, as a
Function("vector-element"). Upon this call I get a sig11: Segmentation
Violation. If I do no normalization I get no violation! So I wonder what
has happened. The code is very short, so I hope someone could look at
it:


unsigned int Nv = FEM::size(mesh, element);
(...)
grad_pde.solve(norml_phi); //When I write norml_phi[0] and norml_phi[1]
to file they look great
Function grad_phi = norml_phi[0];	  
Vector& norml = grad_phi.vector();

for(VertexIterator vertex(mesh); !vertex.end(); ++vertex)
 {
  unsigned int vid = vertex->id();
  real gpx = norml( vid );
  real gpy = norml( vid + Nv);
  real p = std::sqrt( gpx*gpx+gpy*gpy );

  norml( vid ) = gpx/p;
  norml( vid + Nv) = gpy/p;
 }

norml_phi.attach(norml); // I write to VTK-file here and it looks
perfect
(...)

kappa_pde.solve(kappa); // < SIG 11



Best regards,
Dag Lindbo