ffc team mailing list archive

[Martin Sandve Alnæs <martinal@xxxxxxxxx>]

If you're looking at SFC generated code, there
is no such thing as quad rules in the Poisson.h file.
Thus it is unclear to me what you're doing now.

There may be a translation and scaling of the
rules from the .py file to the generated code.
I think the source rules are defined on [-1, 1]
as opposed to the UFC reference cell on [0, 1].

The generated *_integral*.cpp code should have
the scaled quad rules embeddded as arrays.

Martin


On Mon, Jun 22, 2009 at 11:33 PM, Shawn Walker<walker@xxxxxxxxxxxxxxx> wrote:
> Alright.  I'm looking at these quad rules, the 4-pt rule doesn't match the
> weights that show up in the Poisson.h file I have right now.  Also, the
> coordinates seem weird.  Are all of these points evaluated outside the ref
> triangle?
>
> - Shawn
>
> On Mon, 22 Jun 2009, Martin Sandve Alnæs wrote:
>
>> SFC doesn't use the same quadrature rules as
>> FFC, so that makes no sense in my head.
>> Either install SyFi properly with dependencies,
>> or keep using FFC and ignore my suggestion.
>>
>> (If you still want them, the rules SFC use are in
>> site-packages/sfc/quadrature/quad_tables.py)
>>
>> Martin
>>
>>
>>
>> On Mon, Jun 22, 2009 at 11:09 PM, Shawn Walker<walker@xxxxxxxxxxxxxxx>
>> wrote:
>>>
>>> Actually, would it be possible for you to just give me the 4-pt quad rule
>>> on
>>> a triangle.  The problem is, I don't have GiNAC setup, which is needed to
>>> run SyFi, right?
>>>
>>> - Shawn
>>>
>>> On Mon, 22 Jun 2009, Martin Sandve Alnæs wrote:
>>>
>>>> Ok. Temporarily, maybe you'll be happy with the code
>>>> generated by SFC (see the demo/*/cpp/ directories in SyFi).
>>>> There both weights and points are embedded directly in the code.
>>>>
>>>> Martin
>>>>
>>>>
>>>>
>>>> On Mon, Jun 22, 2009 at 10:50 PM, Shawn Walker<walker@xxxxxxxxxxxxxxx>
>>>> wrote:
>>>>>
>>>>>
>>>>> On Mon, 22 Jun 2009, Anders Logg wrote:
>>>>>
>>>>>> I think Shawn just wants to get the quadrature points so he can
>>>>>> hand-modify the code for tabulate_tensor to handle higher-order mapped
>>>>>> elements (to make a prototype for higher-order elements).
>>>>>>
>>>>>> Correct me if I'm wrong.
>>>>>
>>>>> Yes!
>>>>>
>>>>>> In that case, we won't need to make them available since they are
>>>>>> available to the form compiler when the code is being generated, but
>>>>>> it would help if they were available in a comment in the generated
>>>>>> code.
>>>>>
>>>>> I agree that having them in a comment would be good.
>>>>>
>>>>> - Shawn
>>>>>
>>>>>>
>>>>>> On Mon, Jun 22, 2009 at 10:28:29PM +0200, Martin Sandve Alnæs wrote:
>>>>>>>
>>>>>>> On Mon, Jun 22, 2009 at 9:10 PM, Kristian
>>>>>>> Oelgaard<k.b.oelgaard@xxxxxxxxxx> wrote:
>>>>>>>>
>>>>>>>> Quoting Shawn Walker <walker@xxxxxxxxxxxxxxx>:
>>>>>>>>
>>>>>>>>> Actually, I am still a little confused.  Whenever you compute an
>>>>>>>>> integral
>>>>>>>>> by quadrature, you need to evaluate the integrand at the quadrature
>>>>>>>>> points.  Those are the points I need.
>>>>>>>>
>>>>>>>> If you have a quadrature element in your form
>>>>>>>>
>>>>>>>> element = FiniteElement("Quadrature", triangle, 2)
>>>>>>>>
>>>>>>>> you can call the
>>>>>>>> tabulate_coordinates() function of the dof_map associated with the
>>>>>>>> quadrature
>>>>>>>> element. If you don't have a quadrature element there is no direct
>>>>>>>> way
>>>>>>>> of
>>>>>>>> getting the quadrature points.
>>>>>>>>
>>>>>>>>> I just need the quad rule that is used in a particular case.  I see
>>>>>>>>> the
>>>>>>>>> weights are defined in the tabulate_tensor routine.  Are the points
>>>>>>>>> listed
>>>>>>>>> in a comment somewhere?
>>>>>>>>
>>>>>>>> No, currently not. But it might be a natural thing to have. I'll
>>>>>>>> look
>>>>>>>> into it.
>>>>>>>
>>>>>>> It could be an idea to make it available through UFC,
>>>>>>> but then again each ufc::*_integral may use different
>>>>>>> quadrature rules for different terms...
>>>>>>> However, an exception can be thrown if there is no unique rule in
>>>>>>> use.
>>>>>>>
>>>>>>> Martin
>>>>>>> _______________________________________________
>>>>>>> FFC-dev mailing list
>>>>>>> FFC-dev@xxxxxxxxxx
>>>>>>> http://www.fenics.org/mailman/listinfo/ffc-dev
>>>>>
>>>>> _______________________________________________
>>>>> FFC-dev mailing list
>>>>> FFC-dev@xxxxxxxxxx
>>>>> http://www.fenics.org/mailman/listinfo/ffc-dev
>>>>>
>>>>>
>>>>
>>>
>>
>