How to get the vertex corodinates of all DG0 cells in a mesh

Please provide a complete minimal code example.

Also there is a method in the DofMap object for exactly this purpose.

   DofMap::tabulate_coordinates;

The DofMap resides within a FunctionSpace.

Johan

On 05/21/2012 10:05 PM, Jason wrote:
> New question #198006 on DOLFIN:
> https://answers.launchpad.net/dolfin/+question/198006
>
> Hi,
>
> Is this the correct way to get the coordinates of the vertices of all DG0 cells that make up a mesh? Am I also correct in assuming for DG0 cells, there's just a single vertex in the center?
>
> for (CellIterator cell(mesh); !cell.end(); ++cell) {
> xy = new Array<double>(dim, geometry.x(cell->index()));
>
>
> std::cout<< (*xy)[0]<< "\t"<< (*xy)[1]<< "\t"<< (*xy)[2]<< std::endl;
>
> Point point( (*xy)[0], (*xy)[1], (*xy)[2] );
> vec.push_back( point );
> }
>
> This prints out some normal values and aslo some very small ones leading me to think the above is not correct.
>
> Thanks,
>
> Jason
>

Hi Johan,

Here's a minimal code examle, I'm not sure it's correct:

#include <dolfin.h>

using namespace dolfin;

int main()
{
 int dim = 3;

 // Create mesh
 Box mesh(0.0, 0.0, 0.0, 100.0, 100.0, 30.0, 100, 10, 30 );

 MeshGeometry& geometry = mesh.geometry();

 Array<double> *xy;
 int i = 0, c = 0;
 for ( CellIterator cell(mesh); !cell.end(); ++cell ) {
  //Iterate through all vertices in cell
  xy = new Array<double>(dim, geometry.x(cell->index()));

  if (i%1000 == 0) {
   std::cout << c << "\t" << (*xy)[0] << "\t" << (*xy)[1] << "\t" << (*xy)[2] << "\t" << std::endl;
   ++c;
  }

  ++i;
 }
}

Am I correct in assuming for DG0 cells, there's just a single vertex in the center?

Jason

Thanks Johan Hake, that solved my question.