Re: [Getfem-users] High level generic assembly procedures

[Marco Pischedda]

Hi,

how can I impose the boundary condition with high level generic
assembly? For example I want to assemble "Grad_u.Test_p +
p.Grad_Test_u+p.Test_u" and then imposing the value of p on the
boundaries of the 1d domain, i.e x=0 and x=L. It is possible
to write "Grad_u.Test_p +p.Grad_Test_u+p.Test_u + p(0)u(0)-p(L)u(L)",
i.e can I insert the boundaries conditions in the assembling string?

Thanks in advance

Marco


2014-04-03 9:52 GMT+02:00 Marco Pischedda <address@hidden>:
> Dear Yves,
>
> thank you for bug correction, now it works.
>
>> Concerning your question on Grad_u for a vector field, it is usually an
>> order two  tensor (a matrix) except in 1D.
>   Ok that's good.
>
> I will let you know if there are other problems.
>
> Thank you
>
> Marco
>
> 2014-04-03 9:25 GMT+02:00 Yves Renard <address@hidden>:
>>
>>
>> Dear Marco,
>>
>> Concerning your question on Grad_u for a vector field, it is usually an
>> order two  tensor (a matrix) except in 1D.
>> I tried to to the best to make the most operations "dimension
>> indepedent" so there is some permitivity in the langage (components of
>> size 1 are sometimes ignored).
>> Remember also that you can have the expression of any term with the
>> commant Print. For instance "Print( Grad_u).Test_p" will print the
>> gradient of u on each Gauss point. It does a lot of print, but at least,
>> you can see the format of the term.
>>
>> Yves.
>>
>>
>> Le 02/04/2014 17:21, Marco Pischedda a écrit :
>>> Hi,
>>>
>>> I have other questions:
>>>
>>> - I tried to assemble separately the following terms:
>>>   "Grad_u.Test_p" , "p.Grad_Test_u", "p.Test_u" and the code works 
>>> correctly.
>>>   Then I want to assemble the sum of this terms, i.e: "Grad_u.Test_p +
>>> p.Grad_Test_u+p.Test_u"
>>>   but I receive the following error:
>>>
>>>    Addition or substraction of incompatible expressions or of different 
>>> sizes
>>>    terminate called after throwing an instance of 'gmm::gmm_error'
>>>    what():  Error in getfem_generic_assembly.cc, line 3591 :
>>>    Error in assembly string
>>>    Aborted
>>>
>>> - I'm working in 1d problem with vectors as unknowns. Grad_u is
>>> therefore a vector or is a        tensor? When I do Grad_u.Test_p the
>>> result is a scalar or a vector? Test_p is a vector or a scalar?
>>>
>>> Thanks in Advance
>>>
>>> Marco
>>>
>>>
>>>
>>> 2014-04-01 17:51 GMT+02:00 Marco Pischedda <address@hidden>:
>>>> Ok thank you,
>>>>
>>>> I tried it and it works. I will let you know if there are other problems.
>>>>
>>>> Thanks
>>>>
>>>> Marco
>>>>
>>>> 2014-04-01 17:16 GMT+02:00 Yves Renard <address@hidden>:
>>>>> Dear Marco,
>>>>>
>>>>> All seems to me correct in your implementation. This is probably just
>>>>> the test line 2074 of getfem_generic_assembly.cc
>>>>> which is not correct for one-dimensionnal problems.
>>>>>
>>>>> I think the test should be
>>>>>
>>>>>  GA_DEBUG_ASSERT((qdim == 1 && t.sizes()[0] == N) ||
>>>>>                       (t.sizes()[1] == N && t.sizes()[0] == qdim) ||
>>>>>                       (N == 1 && t.sizes()[0] == qdim),
>>>>>                       "dimensions mismatch");
>>>>>
>>>>> May be you can try this. I will validate it if it works.
>>>>>
>>>>> Regards,
>>>>>
>>>>> Yves.
>>>>>
>>>>>
>>>>>
>>>>> Le 01/04/2014 16:56, Marco Pischedda a écrit :
>>>>>> Dear Yves,
>>>>>>
>>>>>> thank you for your fast answer.
>>>>>>
>>>>>> I have another question:
>>>>>>
>>>>>> - I have a monodimensional problem but the unknowns are vectorial. I
>>>>>> set the vectorial
>>>>>> dimension of the unknows with mf_u.set_qdim(3) and with mf_p.set_qdim(3).
>>>>>> When I define the expression " Grad_u.Test_p "  i receive the following 
>>>>>> error:
>>>>>>
>>>>>> terminate called after throwing an instance of 'gmm::gmm_error'
>>>>>>   what():  Error in
>>>>>> ../../getfem-svn/getfem/src/getfem_generic_assembly.cc, line 2074 :
>>>>>> dimensions mismatch
>>>>>>
>>>>>> Grad_u should be a 2nd order tensor, while Test_p should be a vector.
>>>>>> I suppose the
>>>>>> problem is that Grad_u is interpreted as a vector while Test_p is
>>>>>> interpreted as a scalar.
>>>>>> How can I use the high level generic assembly procedures on vectorial 
>>>>>> problems
>>>>>> defined on a monodimensional computational domain?
>>>>>>
>>>>>> Thanks in advance
>>>>>>
>>>>>> Marco
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> 2014-04-01 8:42 GMT+02:00 Yves Renard <address@hidden>:
>>>>>>> Dear Marco,
>>>>>>>
>>>>>>> Yes, your code is correct and it should work correctly.
>>>>>>> Note that you can also use the high level generic assembly with the
>>>>>>> model object using a generic assembly brick.
>>>>>>> Note also that high level assembly is only available in the svn
>>>>>>> repository version of Getfem
>>>>>>> (and a very recent version, at least r4570 because a bug have been
>>>>>>> corrected on coupled problems recently).
>>>>>>>
>>>>>>> Yves.
>>>>>>>
>>>>>>>
>>>>>>> Le 31/03/2014 14:00, Marco Pischedda a écrit :
>>>>>>>> Dear all,
>>>>>>>>
>>>>>>>> I want to use the high level generic assembly procedures in order to
>>>>>>>> use the automatic differentation for calculating the Jacobian of a
>>>>>>>> non-linear problem.
>>>>>>>>
>>>>>>>> For example I want to calculate the Jacobian of two vectorial
>>>>>>>> equations in the unknowns "u" and "p". The first vectorial equation is
>>>>>>>> (u+p).Test_u while the second is (u+p).Test_p.
>>>>>>>>
>>>>>>>>  It is correct the following code?
>>>>>>>>
>>>>>>>>  gmm::sub_interval Iu(0, ndofs_u);
>>>>>>>>  gmm::sub_interval Ip(ndofs_u,ndofs_p);
>>>>>>>>  workspace.add_fem_variable("u", mf_u, Iu, U);
>>>>>>>>  workspace.add_fem_variable("p", mf_p, Ip, P);
>>>>>>>>  workspace.add_expression("(u+p).Test_u + (u+p).Test_p",mim);
>>>>>>>>  getfem::model_real_sparse_matrix Jac(ndofs_u+ndofs_p, 
>>>>>>>> ndofs_u+ndofs_p);
>>>>>>>>  workspace.set_assembled_matrix(Jac);
>>>>>>>>  workspace.assembly(2);
>>>>>>>>
>>>>>>>> In the matrix Jac I have the Jacobian of the system?
>>>>>>>>
>>>>>>>>
>>>>>>>> Thanks in advance
>>>>>>>>
>>>>>>>> Marco
>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>>>> Getfem-users mailing list
>>>>>>>> address@hidden
>>>>>>>> https://mail.gna.org/listinfo/getfem-users
>>>>>>> --
>>>>>>>
>>>>>>>   Yves Renard (address@hidden)       tel : (33) 04.72.43.87.08
>>>>>>>   Pole de Mathematiques, INSA-Lyon             fax : (33) 04.72.43.85.29
>>>>>>>   20, rue Albert Einstein
>>>>>>>   69621 Villeurbanne Cedex, FRANCE
>>>>>>>   http://math.univ-lyon1.fr/~renard
>>>>>>>
>>>>>>> ---------
>>>>>>>
>>>>>
>>>>> --
>>>>>
>>>>>   Yves Renard (address@hidden)       tel : (33) 04.72.43.87.08
>>>>>   Pole de Mathematiques, INSA-Lyon             fax : (33) 04.72.43.85.29
>>>>>   20, rue Albert Einstein
>>>>>   69621 Villeurbanne Cedex, FRANCE
>>>>>   http://math.univ-lyon1.fr/~renard
>>>>>
>>>>> ---------
>>>>>
>>
>>
>> --
>>
>>   Yves Renard (address@hidden)       tel : (33) 04.72.43.87.08
>>   Pole de Mathematiques, INSA-Lyon             fax : (33) 04.72.43.85.29
>>   20, rue Albert Einstein
>>   69621 Villeurbanne Cedex, FRANCE
>>   http://math.univ-lyon1.fr/~renard
>>
>> ---------
>>