# Copyright (C) 2006 Garth N. Wells.# Licensed under the GNU LGPL Version 2.1.## First added:  2006-08-18# Last changed:## Bilinear form a(v, U) for vector-valued Poisson equation#element = VectorElement("Lagrange", "triangle", 1)v = TestFunction(element)U = TrialFunction(element)# Use symmetric gradient to increase coupling which is more demanding# for matrix assemblydef symgrad(v):    return 0.5 * (grad(v) + transp(grad(v)))a = dot(symgrad(v), symgrad(U))*dx