Dealing with heterogeneous structures
by Peter17
Dear Andreas,
2011/4/21 Andreas Kloeckner <lists(a)informa.tiker.net>:
>
> What you want to do is perfectly possible, just not in the way you
> think. :) First of all, each "Field" necessarily has to correspond to a
> scalar field. *But* you are free to make these variables up as you
> please, as long as you provide values for them at evaluation time. So
> instead of Field('material').mu, say Field('mu'), and then, at
> evaluation time, say
>
> op(arg1=value, **kwargs)
>
> where kwargs is a dictionary of these values. Fortunately, Python is
> flexible enough that you can easily make such a dictionary from whatever
> source, be it an object or whatever else.
>
> One caveat: Getting these variables into fluxes might be a bit
> cumbersome, as these are applied to a vector of scalar fields--thus
> each of them must have a numerical index, so you need a convention for
> packing them into a vector.
>
Thank you very much for those informations. I think I need a few more
details so I can make my code work. I have tried different
possibilities but I'm afraid I'm still thinking the wrong way, so,
there are things I still don't understand...
I have objects (material1, material2...) which contain the constants
(material1.C, material2.C, material1.mu, etc.) that I need to access
when calculating the fluxes. C is a 6x6 matrix.
1) Do I need to create a space-dependent function for each constant
(I'd like not to), or can I rely on Field() to make only "a reference
to the material object" be space-dependent?
i.e. Can I use this?
material_elements = {}
for key in materials.keys():
material_elements[key] = set(mesh_data.tag_to_elements[key])
def mat_val(x, el):
for key in materials.keys():
if el in material_elements[key]:
return key
raise ValueError, "Material not found for this element"
op = MyOperator(dim=dim,
mat_val = make_tdep_given(mat_val),
materials = materials,
...
)
And, then, materials[material].mu, materials[material].C
Or do I need a C_val, mu_val, etc.?
2) I have packed this in a vector, so, I have:
def __init__(self,
dim,
mat_val,
materials,
...
):
self.mat_val = mat_val
...
# In rsh:
constants = self.mat_val
return compiled_op_template(q=q,constants=constants,**extra_kwargs)
# ^^^^^ Is this right? I am not touching extra_kwargs...
# In op_template:
q = make_vector_field('q', dim+self.dimF[dim])
constants = make_vector_field('constants', 1)
material = constants
# In the flux calculation, I try to access materials[material].mu but I get:
TypeError: unhashable type: 'numpy.ndarray'
# Probably because:
print material
# Prints
[constants[0]]
# However, if I replace self.materials[material].mu by
self.materials[material[0]].mu, I get:
KeyError: Subscript(Variable('constants'), 0)
What am I doing wrong?
3) I have read http://wiki.tiker.net/Hedge/HowTo/DealingwithOperators
but I don't understand when exactly I have to use Field() and when I
can pass the values in function calls...
I'm sorry to disturb you about this, but I have spent a full week on
this without managing to have it work... I feel lost :)
Thanks in advance
Best regards
--
Peter Potrowl
8 years
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