Subject: [Ffc] Symmetric TensorElement

From: Kaspar Müller <[email-masked]>
Date: Tue, 01 Dec 2009 16:58:33 -0800

Hi,

I'm trying to use symmetric TensorElements as described in the 
ufl-user-manual.pdf (version0.3) on page 16.
The head of my UFL file looks like:
---------------------------------------------------------------------------------------------------
cell = triangle

T = TensorElement("Lagrange", cell, 1, symmetry=True)
V = VectorElement("Lagrange", cell, 1)
P = FiniteElement("Lagrange", cell, 1)

ME = MixedElement(V,P,T)

vqt = TestFunction(ME)
v, q, tau = split(vqt)

ups = TrialFunction(ME)
u, p, sigma = split(ups)

...
---------------------------------------------------------------------------------------------------

and I get the following error message:

---------------------------------------------------------------------------------------------------
Compiler stage 4: Generating code
---------------------------------
  Generating code using quadrature representation.
 
  Generating code for cell integrals.
Unable to extract sub element for component 6 of Mixed finite element: 
[Mixed finite element: [FiniteElement('Lagrange', 'triangle', 1), 
FiniteElement('Lagrange', 'triangle', 1)], FiniteElement('Lagrange', 
'triangle', 1), Mixed finite element: [FiniteElement('Lagrange', 
'triangle', 2), FiniteElement('Lagrange', 'triangle', 2), 
FiniteElement('Lagrange', 'triangle', 2)]].
 
*** FFC: Unable to extract sub element for component 6 of Mixed finite 
element: [Mixed finite element: [FiniteElement('Lagrange', 'triangle', 
1), FiniteElement('Lagrange', 'triangle', 1)], FiniteElement('Lagrange', 
'triangle', 1), Mixed finite element: [FiniteElement('Lagrange', 
'triangle', 2), FiniteElement('Lagrange', 'triangle', 2), 
FiniteElement('Lagrange', 'triangle', 2)]].
*** FFC: To get more information about this error, rerun FFC with --debug.
---------------------------------------------------------------------------------------------------

Are symmetric TensorElements not supported by FFC?

Thanks for help.

Cheers,
Kaspar

---

From: "Garth N. Wells" <[email-masked]>
Date: Wed, 02 Dec 2009 07:18:51 +0000

> The head of my UFL file looks like:

Tensor elements and functions are largely untested in both FFC and
DOLFIN. We have a Blueprint on this topic for FFC

    https://blueprints.launchpad.net/ffc/+spec/tensor-functions

Garth

> Thanks for help.
> 
> Cheers,
> Kaspar
> 
> 
> 
> 
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