dolfin team mailing list archive

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

The thread on the new Function design has digressed from the immediate 
issue, so I'm restarting it.

The issue is how to deal with user defined functions in C++. What if we 
have a design such that:

- All Functions must have a FunctionSpace

- A FunctionSpace does not have to be complete (a complete FunctionSpace 
having a Mesh, a FiniteElement and a DofMap). As a minimum requirement, 
and FunctionSpace must have a Mesh.

- A FiniteElement and/or DofMap can be attached to a FunctionSpace after 
its creation


Related to the functions Function::interpolate(double* coefficients, ..) 
for interpolating Functions on cells

- The new Function::interpolate functions do not take a FiniteElement as 
an argument, so it is not possible to interpolate a function in a 
different space. Is it desirable to allow Functions from one space to be
interpolated in another?

If we do this, would:

- The above allow FiniteElement types to be checked at runtime for 
consistency (the FiniteElement passed to Function::interpolate should be 
the same as the Functions own FiniteElement for discrete Functions. This 
is what we did with the old design.)>

- The above deal with the issue of user-defined functions which have a a 
FunctionSpace but no FiniteElement?

- The above deal with special functions, like the mesh size h?

Garth