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

[Marco Pischedda]

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
>>
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>
>
> --
>
>   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
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