ufl team mailing list archive

[Martin Sandve Alnæs <martinal@xxxxxxxxx>]

On Fri, Feb 13, 2009 at 2:03 PM, Kristian Oelgaard
<k.b.oelgaard@xxxxxxxxxx> wrote:
> 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

Attaching metadata to an integral is implemented, but we
haven't  decided what format the metadata should be in.

This currently works:

metadata = "arbitrary data"
metadata2 = "other arbitrary data"

a = f*dx(0, metadata) + g*dx(0, metadata2) + g*dx(0, metadata)

which will result in a Form with two Integrals with integrands
(f+g) and (g) since the first and last term has the same domain and data.

Martin