vectorpoisson.form

利用C

# 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 assembly

def symgrad(v):
    return 0.5 * (grad(v) + transp(grad(v)))

a = dot(symgrad(v), symgrad(U))*dx