Question about how the adjoint equations are generated

[Miguel Salazar]

Hello

Does dolfin-adjoint generate the adjoint equations every time the gradient in the ReducedFunctional object is called? I have checked out the main papers published with this library and it is still not clear to me. I know that there is a tape with the forward equation solves that is saved by dolfin-adjoint. Is there a similar tape with the adjoint equations? I imagine this tape could be used by the gradient evaluation several times. Specially for optimization problems. Is this the case? Thanks.

[Simon Funke]

Hi Migue,

Yes, dolfin-adjoint derives the tangent-linear/adjoint and higher order adjoint equations every time.

The reasoning behind this is that this action requires only symbolic UFL manipulations. The computational cost of these are typically neglectable compared to the assembly and solve routines.

Simon