[Getfem-users] VTK export -- bug or feature ?

[Roman Putanowicz]

Dear All,

Have you experienced similar problems as the described below?

It seems that the output of vtk_export for vectorial elements
depends on the dimension of the mesh (geometric dimension, mesh.dim()
I meant).

For the following test code:

    getfem::mesh mesh;

    std::vector<bgeot::size_type> ind(4);
    ind[0] = mesh.add_point(bgeot::base_node(0.0, 0.0,0.0));
    ind[1] = mesh.add_point(bgeot::base_node(0.5, 0.0,0.0));
    ind[2] = mesh.add_point(bgeot::base_node(1.0, 0.0,0.0));
    ind[3] = mesh.add_point(bgeot::base_node(2.0, 0.0,0.0));
    
    mesh.add_segment(ind[0], ind[1]);
    mesh.add_segment(ind[1], ind[2]);
    mesh.add_segment(ind[2], ind[3]);
   
    getfem::mesh_fem fem(mesh);
    fem.set_qdim(2);
    fem.set_finite_element(getfem::fem_descriptor("FEM_PK(1,1)"));

    getfem::size_type Ndof = fem.nb_dof();
    
    std::vector<double> V(Ndof);
    for (getfem::size_type i=0; i<Ndof; i++) {
      V[i] = i+1;
    }

    getfem::vtk_export out(std::cout, true);
    out.set_header("ala");
    out.exporting(fem);
    out.write_point_data(fem, V, "u");

I got different results depending if mesh is 3 dimensional or 2 dimensional,
( 2D mesh is created using 2 coordinates in call to 
  bgeot::base_node(0.0, 0.0)
)

For 2D mesh the vector field saved looks like:
VECTORS u float
 1 2 0 3 4 0 5 6 0 7 8 0

which is what I have expected but for 3D mesh it looks like:
VECTORS u float
 1 2 3 3 4 5 5 6 7 7 8 0

which seems to be wrong.

Regards

Roman
-- 
Roman Putanowicz, PhD  < address@hidden  >
interpolated with Hermite FEM).
Institute for Computational Civil Engng (L-5)
Dept. of Civil Engng, Cracow Univ. of Technology
www.l5.pk.edu.pl, tel. +48 12 628 2569, fax 2034