dolfin team mailing list archive

[Shawn Walker <walker@xxxxxxxxxxxxxxx>]

For the interpolation between different spaces, is it not possible to have 
a routine that traverses the mesh cell-by-cell, and computes the 
interpolant (in space A) from the function in space B by using the 
coordinates of the DoF from space A? 
This may only work for largrange type elements; elements like 
Raviart-Thomas would be more difficult.

- Shawn

On Wed, 22 Oct 2008, Garth N. Wells wrote:

> 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
>
>
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