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

[Marco Pischedda]

Ok,

thank you. I have some problem with the function
sinc(sqr(rho(1))+sqr(rho(2))+sqr(rho(3))), I receive this error:

"Unknown variable, function, operator or data"
terminate called after throwing an instance of 'gmm::gmm_error'
  what():  Error in
../../getfem-svn/getfem/src/getfem_generic_assembly.cc, line 4269 :
Error in assembly string


rho is a finite element variable, i.e
workspace.add_fem_variable("rho", mf_rho, Irho, rho);

Thanks

Marco

2014-04-14 11:34 GMT+02:00 Yves Renard <address@hidden>:
>
> Dear Marco,
>
> May be it is too much specific to add a new function to the langage (you
> may if you think it is better). However, you also may use
> (1 -cos(t))/t^2 = (sinc(t))^2 / (1+cos(t))
>
>
> Yves.
>
>
>
>
>
> Le 14/04/2014 11:23, Marco Pischedda a écrit :
>> Dear Yves,
>>
>> thank you for your answer.
>> Is there also something for the function (1-cos(phi))/(phi*phi) when
>> phi tends to zero?
>>
>> Thanks in advance
>>
>> Marco
>>
>>
>>
>> 2014-04-13 10:44 GMT+02:00 Yves Renard <address@hidden>:
>>> Dear Marco,
>>>
>>> The message "WARNING: detected wrong equivalent nodes" is a debugging 
>>> message which can be ignored, it serves to control the efficiency of the 
>>> hash codes for the semantic trees produced by the generic assembly.
>>>
>>> For the moment, their is no conditional expressions in the language. 
>>> However, you can use pos_part and neg_part.
>>> Concerning the cardinal sine function (sin(t)/t) I added it to the 
>>> language. It is called "sinc" now in the generic assembly.
>>>
>>> Yves.
>>>
>>>
>>>
>>>
>>>
>>> ----- Original Message -----
>>> From: "Marco Pischedda" <address@hidden>
>>> To: "Yves Renard" <address@hidden>
>>> Cc: address@hidden
>>> Sent: Friday, April 11, 2014 9:28:22 AM
>>> Subject: Re: [Getfem-users] High level generic assembly procedures
>>>
>>> Dear Yves,
>>>
>>> thank you for your answer.  I understand how to impose the boundary 
>>> condition.
>>> I have another question: in my formulation I'm assembling a term
>>> A(rho)*f.Test_f, where A(rho) is a symmetric matrix defined as
>>> follows:
>>>
>>>  " [-sqr(rho(2))-sqr(rho(3)), rho(1)*rho(2), rho(1)*rho(3);"
>>>  " rho(1)*rho(2), -sqr(rho(1))-sqr(rho(3)), rho(2)*rho(3);"
>>>  " rho(1)*rho(3), rho(2)*rho(3) , -sqr(rho(1))-sqr(rho(2))]";
>>>
>>> where rho and f are two FemVariables. When I'm assembling this term I
>>> receive this warning message:  "WARNING: detected wrong equivalent
>>> nodes".
>>> What does it mean?
>>>
>>> Then I have an expression "sin(phi)/phi", how can I insert an "if
>>> condition" (i.e if phi<1e-8) in the expression when "phi" tends to
>>> zero?
>>>
>>> Thanks in advance
>>>
>>> Marco
>>>
>>>
>>>
>>> 2014-04-08 15:29 GMT+02:00 Yves Renard <address@hidden>:
>>>>
>>>> Dear Marco,
>>>>
>>>> No, "Grad_u.Test_p +p.Grad_Test_u+p.Test_u + p(0)u(0)-p(L)u(L)" is not
>>>> valid. The expression of an assembly string is to be evaluated at each
>>>> Gauss point of the concerned region. An expression such as "p(0)" will
>>>> be understand to be the component 0 of p which is not valid because the
>>>> first component is 1.
>>>> If you want to add some expression on a boundary (an extremity of the
>>>> intervall [0, L] here) then it is possible but not in the same assembly
>>>> string. In your example you have to add the assembly string "p.u" at the
>>>> boundary x=0 and "-p.u" at the boundary x=L.
>>>>
>>>> However, if you need to prescribe a Dirichlet boundary condition, the
>>>> best would be to use a corresponding model brick (if you use the model
>>>> system).
>>>>
>>>>
>>>> Yves.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> Le 07/04/2014 15:43, Marco Pischedda a écrit :
>>>>> 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
>>>>>>>
>>>>>>> ---------
>>>>>>>
>>>>
>>>> --
>>>>
>>>>   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
>
> ---------
>