ufl team mailing list archive

[Kristian Oelgaard <k.b.oelgaard@xxxxxxxxx>]

On 30 January 2010 11:56, Garth N. Wells <gnw20@xxxxxxxxx> wrote:
> In the UFL manual, there is a section on 'conditionals' (sec 2.11) but
> I'm unsure of the what the intention is. Is the idea that they can be
> used in forms? It would be really useful if I could do something like:
>
>  un   = dot(u, n)
>  cond = lt(un, 0.0)
>
> and use 'cond' (= 0 or 1) in a form.

As I recall it, we (you and I) thought it would be nice to have conditionals so we could use it to determine if a facet was an outflow facet or not at runtime in the generated C++ code. I think the idea was to simply translate the conditionals in a form into

if ( condition )
{
 do something
}  

blocks in the generated code.
However, due to other improvements in the UFL language we can now determine the outflow facets in a more elegant way, in my opinion, so we didn't look further into the conditionals. That being said, there might be other cases where it will still be useful.

Kristian
> Garth
>
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