Comment 3 for bug 868255

On 5 October 2011 14:12, Gerd Wachsmuth
<email address hidden> wrote:
> No, I didn't do any profilings.

This bug should probably be filed in FFC instead, but please support
any 'overhead' claims with at least some simple profiling.

The fix to optimise expressions inside operators like 'sqrt', 'ln',
'sin' etc. is non-trivial in the current quadrature implementation and
will not be addressed before 1.0 is released.

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> https://bugs.launchpad.net/bugs/868255
>
> Title:
>  Using sym() results in overhead
>
> Status in Unified Form Language:
>  Confirmed
>
> Bug description:
>  If I use the function sym() to assemble a form containing the
>  symmetric part of a matrix, the (1,1)-element of the matrix gets
>  represented as "2*A[1,1]/2" or "(A[1,1]+A[1,1])/2". This induces
>  overhead when assembling the FE matrices.
>
>  For instance, compiling
>
>  element = TensorElement("CG", triangle, 1)
>  A = Coefficient(element)
>  B = Coefficient(element)
>
>  a = sqrt(inner(sym(A),sym(B)))*dx
>
>  with ffc (optimization turned on with -O), the header file contains
>  something like "(F0 + F0)/2.000000000000000*(F1 +
>  F1)/2.000000000000000".
>
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