UFL Specification and User Manual 0.3 - FEniCS Project

UFL Specification and User Manual 0.3Martin S. Alnæs, Anders Loggf = energy_norm(a, w)which is equivalent tof = action(action(a, w), w)2.13.4 Adjoint of a bilinear FormThe adjoint a ′ of a bilinear form a is defined asa ′ (u,v) = a(v,u).This operation is implemented in UFL simply by swapping test and trialfunctions in a Form, and is used like this:aprime = adjoint(a)2.13.5 Linear and bilinear parts of a FormSome times it is useful to write an equation on the formata(v,u)−L(v) = 0.Before we can assemble the linear equationAu = b,we need to extract the forms corresponding to the left hand side and righthand side. This corresponds to extracting the bilinear and linear terms ofthe form respectively, or the terms that depend on both a test and a trialfunction on one side and the terms that depend on only a test function onthe other.This is easily done in UFL using lhs and rhs:52