dolfin team mailing list archive

["Garth N. Wells" <gnw20@xxxxxxxxx>]

On 01/06/10 17:07, Anders Logg wrote:
> On Tue, Jun 01, 2010 at 03:19:50PM +0100, Garth N. Wells wrote:
> > On 01/06/10 15:10, Anders Logg wrote:
> > > What is the difference from before? Is it only that the dofs are
> > > always tabulated and stored (never computed on the fly)?
> >
> > More or less. There are some bug fixes and some missing features
> > have been added (collapsed dof maps for renumbered maps, work in
> > parallel now).
> >
> > It was too complicated (for me at least) to have both tabulated dofs
> > and on the fly computation via UFC in the same class. It's much
> > easier to follow now (which helped in finding some bugs).
> >
> > Garth
>
> Can you remind me of what collapse do? What is a contiguous dofmap?

A sub-dofmap will be, by default, a view into the original dof map. It 
will extract the the relevant indices, but it won't change them. It's 
suitable for when the sub-function shares the vector with the original 
equation, e.g.

  Function& u = U[0];
  Function& p = U[1];  // U, u and p shared the same vector

A collapsed dof map is independent of the original dof map, with the 
lowest index = 0 and the greatest = global_dimension -1. It's used when 
a sub-function is extracted from a Function such that it has it's own 
vector, e.g.

  Function u = U[0]; // u has its own vector
  Function p = U[1]; // p has its own vector

Garth

 > --
> Anders