Assigning values 0 to the variable S in my example leads to a calculation of a gradient of S = 0 everywhere which is correct.
But assigning other constant values (like 1) leads to different results for the gradient of S, not 0 although it should also be.
Just wondered if it has to do with the evaluating function: gradS = pb.evaluate('ev_grad.i2.Omega(S)', S=vv, mode='el_avg') ?

Thx
Djamil

Quinta-feira, 16 de Maio de 2013 12:15:07 UTC+1, dj....@gmx.de escreveu:

Thanks Robert! Works fine.
:)

Quinta-feira, 16 de Maio de 2013 11:31:26 UTC+1, Robert Cimrman escreveu:
On 05/16/2013 11:22 AM, dj....@gmx.de wrote:
> Dear Robert,
> you are right, the parameter S is not used in the equations, so I would
> have to define it. I tried it without success. Do you have an example how
> to define it correctly in the postproc-function?
> I add the code below which gives the mentioned error (argument S not
> found). It's using the rectangle_fine_tri.mesh.

It can be easily created in this way:

vv = pb.create_variables('S')['S']
vv.time_update(None, pb.functions)
gradS = pb.evaluate('ev_grad.i2.Omega(S)', S=vv, mode='el_avg')
out['Grad_S'] = Struct(name='output_S', mode='cell', data=gradS, dofs=None)

The example file works after adding the first two lines into the post_process()
function (notice the modification of the third line!).

Cheers,
r.

> Thanks
> Djamil
>
> Quarta-feira, 15 de Maio de 2013 21:42:37 UTC+1, Robert Cimrman escreveu:
>>
>> Hi!
>>
>> On 05/15/2013 04:46 PM, dj....@gmx.de <javascript:> wrote:
>>> Dear sfepy group,
>>>
>>> I defined a parameter field S and tried to use a function to assign
>> certain
>>> values to the parameter depending of the coordinates.
>>> Like this (simplified):
>>>
>>> variable_7 = {
>>> 'name' : 'S',
>>> 'kind' : 'parameter field',
>>> 'field' : 'pressure',
>>> 'like' : None,
>>> 'special' : {'setter' : 'Def_Sigma'},
>>> }
>>>
>>> def Def_Sigma(ts,coors,region=None):
>>> x = coors[:,0]
>>> y = coors[:,1]
>>> val = x*y*10
>>> return val
>>>
>>> The field is:
>>>
>>> field_1 = {
>>> 'name' : 'pressure',
>>> 'dtype' : nm.float64,
>>> 'shape' : (1,),
>>> 'region' : 'Omega',
>>> 'approx_order' : '1',
>>> }
>>>
>>> When I try to calculate the gradient of the parameter S field in a
>>> post-process-hook I always get an error:
>>>
>>> def post_process(out, pb, state, extend=False):
>>> from sfepy.base.base import Struct
>>>
>>> div = pb.evaluate('ev_grad.i2.Omega(S)',mode='el_avg')
>>> out['Grad_S'] = Struct(name='output_data', mode='cell', data=div,
>>> dofs=None)
>>>
>>> return out
>>>
>>> The error is:
>>> Argument S not found.
>>
>> Is the variable S used in the equations (like, e.g. in [1])? If not, it is
>> not
>> created/set by the solver at all. In that case, you would have to create
>> it
>> manually in the post_process() function.
>>
>> Anyway, it would help if you send a complete file (preferably using one of
>> the
>> sfepy meshes), so that I could run it.
>>
>> r.
>>
>> [1]
>> http://sfepy.org/doc-devel/examples/thermo_elasticity/thermo_elasticity.html
>>
>