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[Martin Sandve Alnæs <question159771@xxxxxxxxxxxxxxxxxxxxx>]

Question #159771 on DOLFIN changed:
https://answers.launchpad.net/dolfin/+question/159771

Martin Sandve Alnæs proposed the following answer:
You can take the derivatives of an UFL expression, but not an
dolfin.Expression (which represents compiled code).

Try this for example:

from dolfin import *
mesh = UnitSquare(20, 20)
cell = mesh.ufl_cell()
x = cell.x
f = sin(2*pi*(x[0]**2 + x[1]**2))
plot(project(grad(f), mesh=mesh))
interactive()

Martin

On 31 May 2011 18:41, Praveen C <question159771@xxxxxxxxxxxxxxxxxxxxx> wrote:
> Question #159771 on DOLFIN changed:
> https://answers.launchpad.net/dolfin/+question/159771
>
> Praveen C gave more information on the question:
> I know I can interpolate and Expression and then take grad. But I am
> looking to see if there is some automatic differentiation of an
> Expression available in dolfin.
>
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