On Fri, Oct 16, 2009 at 03:34:06PM -0400, mspieg wrote: > Hi All, > I'm trying to update a working 0.9.3 code to 0.9.4, and I need to > understand > the new interfaces for Function::eval a bit better. > > I had things working fine with the old interface > > Function::eval (double *values, const double *x, const ufc::cell &ufc_cell, > uint cell_index) > > and am trying to understand how to efficiently use > > Function::eval (double *values, const double *x, const Cell &dolfin_cell, > const > ufc::cell &ufc_cell) > > (My codes need to do a large number of evals at arbitrary points and cells > efficiently) > > among other things, is there an easy way to update the index of a cell, > without > constructing a new Cell every time? (or shouldn't I be worrying about this).
Constructing a cell should not cost that much. It just stores the
index, the dimension and a reference to the mesh.
If you are using iterators over a mesh, then you already have the cell
by dereferencing the pointer. The typical usage would be
UFCCell ufc_cell(mesh);
for (CellIterator cell(mesh); !mesh.end(); ++cell)
{
ufc_cell.update(*cell);
f.eval(values, x, *cell, ufc_cell);
}
But perhaps you don't use iterators?
> Anyway, I need to play with things a bit more, but looking at the source code
> for eval, I was also wondering
> if lines 320 and 321 are required as line 322 doesn't seem to require cell.
>
> typo? bug? or general ignorance on my part (probably the latter).
Yes, lines 320-321 should be removed. Thanks for noticing. I've fixed
this now.
--
Anders
> cheers
> marc
>
> void Function::eval(double* values, const Data& data) const
>
> 00311 {
> 00312 assert(values);
> 00313 assert(_function_space);
> 00314
> 00315 // Check if UFC cell if available and cell matches
> 00316 if (data._dolfin_cell &&
> _function_space->has_cell(*data._dolfin_cell))
> 00317 {
> 00318 // Efficient evaluation on given cell
> 00319 assert(data._ufc_cell);
> 00320 const uint cell_index =
> data._ufc_cell->entity_indices[data._ufc_cell->topological_dimension][0];
> 00321 Cell cell(_function_space->mesh(), cell_index);
> 00322 eval(values, data.x, *data._dolfin_cell, *data._ufc_cell);
> 00323 }
> 00324 else
> 00325 {
> 00326 // Redirect to point-based evaluation
> 00327 eval(values, data.x);
> 00328 }
> 00329 }
>
> ----------------------------------------------------
> Marc Spiegelman
> Lamont-Doherty Earth Observatory
> Dept. of Applied Physics/Applied Math
> Columbia University
> http://www.ldeo.columbia.edu/~mspieg
> tel: 845 704 2323 (SkypeIn)
> ----------------------------------------------------
>
>
> _______________________________________________
> DOLFIN-dev mailing list
> DOLFIN-dev@fenics.org
> http://www.fenics.org/mailman/listinfo/dolfin-dev
signature.asc
Description: Digital signature
_______________________________________________ DOLFIN-dev mailing list DOLFIN-dev@fenics.org http://www.fenics.org/mailman/listinfo/dolfin-dev
