ffc team mailing list archive

["Garth N. Wells" <gnw20@xxxxxxxxx>]

Kaspar Müller wrote:
> 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?
>

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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