Hi,
ffc looks for the variables a, L or M to generate a form, so you should
use L instead of L2, so that ffc notices it.
regards,
patrick
Jehanzeb Hameed wrote:
> I cant figure out how to generate a form file for norm, in C++. The
> problem is that the form is quadratic in its arguments, and so isn't a
> valid form according to ffc user manual. I tried it anyway, making a
> file like this (just for testing):.
>
> vecElement = VectorElement("Lagrange", "triangle", 1,3)
> u = Function(vecElement)
> L2 = dot(u,u)*dx
>
> ffc doesnt make .h file, and exits with the following message:
>
> "No forms or elements specified, nothing to do."
>
> I tried compiling by "ffc -r quadrature l2norm.form", and again got
> the same message.
>
> Can someome please help amd point out what I can do?
>
> Thanks,
> -Jehanzeb
>
> On Wed, Jun 10, 2009 at 11:14 AM, Anders Logg<l...@simula.no> wrote:
>> On Wed, Jun 10, 2009 at 09:58:20AM -0500, Jehanzeb Hameed wrote:
>>> Thanks. So I guess that means no such facility is available in C/C++ ?
>> No, since the computation depends on the space the functions are in
>> and so the code needs to be generated. In C++, you need to define a
>> form file for the norm. Look at
>>
>> site-packages/dolfin/norm.py
>>
>> for how to define the norms.
>>
>> --
>> Anders
>>
>>
>>> On Wed, Jun 10, 2009 at 2:03 AM, Anders Logg<l...@simula.no> wrote:
>>>> On Tue, Jun 09, 2009 at 05:11:48PM -0500, Jehanzeb Hameed wrote:
>>>>> Hello,
>>>>>
>>>>> Is there a builtin function in dolfin to compute L^2 or H_1 norms? If
>>>>> so, can you please point it out. If not, are there support functions
>>>>> (e.g. a Gauss Quadrature table, computation of Jacobians, etc) which
>>>>> can help in this?
>>>> Yes, this is available in the DOLFIN Python interface:
>>>>
>>>> norm(v)
>>>>
>>>> The default computes the L^2 norm. Several options are available:
>>>>
>>>> L^2: norm(v, 'L2')
>>>> H^1: norm(v, 'H1') includes L^2 term
>>>> H^1_0: norm(v, 'H10') does not include L^2 term
>>>> H(div): norm(v, 'Hdiv') includes L^2 term
>>>> H(div): norm(v, 'Hdiv0') does not include L^2 term
>>>> H(curl): norm(v, 'Hcurl') includes L^2 term
>>>> H(curl): norm(v, 'Hcurl0') does not include L^2 term
>>>>
>>>>
>>>> -----BEGIN PGP SIGNATURE-----
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>>>>
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>>>> =so4c
>>>> -----END PGP SIGNATURE-----
>>>>
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>> -----BEGIN PGP SIGNATURE-----
>> Version: GnuPG v1.4.9 (GNU/Linux)
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>> =a7iu
>> -----END PGP SIGNATURE-----
>>
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