derivative(form, u, du=None, coefficient_derivatives=None)¶
UFL form operator: Compute the Gateaux derivative of form w.r.t. coefficient in direction of argument.
If the argument is omitted, a new Argument is created in the same space as the coefficient, with argument number one higher than the highest one in the form.
The resulting form has one additional Argument in the same finite element space as the coefficient.
A tuple of Coefficients may be provided in place of a single Coefficient, in which case the new Argument argument is based on a MixedElement created from this tuple.
An indexed Coefficient from a mixed space may be provided, in which case the argument should be in the corresponding subspace of the coefficient space.
If provided, coefficient_derivatives should be a mapping from Coefficient instances to their derivatives w.r.t. ‘coefficient’.
A tuple of Coefficients in place of a single Coefficient is not supported in DOLFIN. Supply rather a Function on a mixed space in place of a Coefficient.