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Jacobian computation

–1 vote

In a finite element formulation I have the contribution
$$
\sum_{element} \int_{element} D
\frac{\partial W}{\partial x_i}
\cdot
\frac{\partial U}{\partial x_i}
dx
$$
where U and W are vectors of some trial and test functions.
The computation of D involves terms like
$$
\frac{\partial \xi_l }{\partial x_j}
\cdot
\frac{\partial U}{\partial x_j}
\cdot
A
\frac{\partial \xi_l }{\partial x_k}
\cdot
\frac{\partial U}{\partial x_k}
$$
where $$\xi_l$$ are components of the local coordinates.

How can I get the jacobian $$\displaystyle \frac{\partial \xi }{\partial x}$$ ?

closed with the note: This is not a FEniCS question.
asked Dec 12, 2014 by Thomas FEniCS Novice (150 points)
closed Dec 17, 2014 by Garth N. Wells
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