ufl team mailing list archive

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

Quoting "Garth N. Wells" <gnw20@xxxxxxxxx>:

> 
> 
> Kent Andre wrote:
> > On fr., 2009-02-13 at 13:32 +0100, Martin Sandve Alnæs wrote:
> >> On Fri, Feb 13, 2009 at 1:20 PM, Kristian Oelgaard
> >> <k.b.oelgaard@xxxxxxxxxx> wrote:
> >>> Quoting Martin Sandve Alnæs <martinal@xxxxxxxxx>:
> >>>
> >>>> On Fri, Feb 13, 2009 at 11:53 AM, Kristian Oelgaard
> >>>> <k.b.oelgaard@xxxxxxxxxx> wrote:
> >>>>>
> >>>>> Hello,
> >>>>>
> >>>>> Any thoughts on how to implement a better rule for determining the
> >>>> polynomial
> >>>>> order of a form?
> >>>>>
> >>>>> as it is now the forms:
> >>>>>
> >>>>> a = v*u*dx
> >>>>> a = f*v*u*dx
> >>>>> a = f*f*f*.....*v*u*dx
> >>>>> a = inner(grad(v), grad(u))*dx
> >>>>>
> >>>>> all result in the same order (2 for linear basis functions)
> >>>> What do we want? Add the degrees of all functions and basis functions
> >>>> that are multiplied? Should be possible to do.
> > 
> > In general I don't think this is what you 'want' to do. 
> > It is common to use the same quadrature rules for 
> > a = inner(grad(v), grad(u))*dx
> > and 
> > a = f*inner(grad(v), grad(u))*dx
> > 
> > even though f is a function. 

Sure, but I do believe the default should be correct integration.
If it is possible to have different orders it might have an impact on the
performance of the code which will allow the default for the compilers to be
'correct AND fast' code.
Through the meta data the user is given the opportunity of changing the rules,
typically decreasing the order to gain speed by sacrificing accuracy.
 
> > It would however be nice to choose quadrature rule by setting some kind
> > of meta data. 
> >
> 
> We discussed attaching this data to the integration operators a while 
> ago and there was general agreement.

Yes, and it would not be a problem to override the default values if any
instructions are set.

Kristian


> Garth
> 
> > Kent
> > 
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> 
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