dolfin team mailing list archive

[Jehanzeb Hameed <jhameed2@xxxxxxxxxxxx>]

I imported tetrahedron from dolfin.ufl, is that correct?

I get this error when trying out "element = VectorElement("Lagrange",
tetrahedron, 3)"

Preprocessing form file: l2ErrNorm.form --> l2ErrNorm.py

*** Cell('tetrahedron', 1)
*** To get more information about this error, rerun ffc with the option -d1.



Preprocessing form file: l2ErrNorm.form --> l2ErrNorm.py

*** Cell('tetrahedron', 1)
*** To get more information about this error, rerun ffc with the option -d1.


On Mon, Jun 15, 2009 at 1:21 PM, Anders Logg<logg@xxxxxxxxx> wrote:
> On Mon, Jun 15, 2009 at 01:09:43PM -0500, Jehanzeb Hameed wrote:
>> Thanks. That works. I have a related question about forms.  Can the
>> form be defined in python, and then compiled via ffc? For example, I
>> did,
>>
>> from dolfin import *
>> mesh = Mesh("./mesh_2d.xml")
>> V = VectorFunctionSpace(mesh, "Lagrange", 1,3)
>> u = Function(V)
>> M = dot(u,u)*dx
>>
>>
>> and then called ffc on this form. This generated a header file. Are
>> there any caveats here that I should be careful about?
>>
>> -Jehanzeb
>
> It's plain luck this works at all and the mesh will be completely
> ignored so do I suggest you just write
>
>  element = VectorElement("Lagrange", tetrahedron, 3)
>  u = Function(element)
>  M = dot(u, u)*dx
>
> --
> Anders
>
>
>> > On Mon, Jun 15, 2009 at 10:09:11AM +0200, Patrick Riesen wrote:
>> >> 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.
>> >
>> > Should be M unless you want to assemble a vector.
>> >
>> >
>> >
>> >> 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<logg@xxxxxxxxx> 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.
>> >> >>
>> >> >>
>> >> >>
>> >> >>> On Wed, Jun 10, 2009 at 2:03 AM, Anders Logg<logg@xxxxxxxxx> 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-----
>> >> >>>> Version: GnuPG v1.4.9 (GNU/Linux)
>> >> >>>>
>> >> >>>> iEYEARECAAYFAkovWqUACgkQTuwUCDsYZdGb3gCfa2gWnzealWzkjPoRj8hf3cr/
>> >> >>>> 0EUAoJh4mpaIzRU9eCnnC+XWlupu6SV0
>> >> >>>> =so4c
>> >> >>>> -----END PGP SIGNATURE-----
>> >> >>>>
>> >> >>>> _______________________________________________
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>> >> >> -----BEGIN PGP SIGNATURE-----
>> >> >> Version: GnuPG v1.4.9 (GNU/Linux)
>> >> >>
>> >> >> iEYEARECAAYFAkov28sACgkQTuwUCDsYZdE8KQCdEI7wS27QaNw9knI2U9L+RVST
>> >> >> xeUAnRdLrrhAVzsBn6nO1b6CLEpF64ey
>> >> >> =a7iu
>> >> >> -----END PGP SIGNATURE-----
>> >> >>
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>> > =k8B2
>> > -----END PGP SIGNATURE-----
>> >
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>
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