mixedpoisson.form

利用C

# Copyright (C) 2006-2007 Anders Logg ([e-mail]) and Marie Rognes ([e-mail])"
# Licensed under the GNU LGPL Version 2.1
#
# The bilinear form a(v, u) and linear form L(v) for
# a mixed formulation of Poisson's equation with BDM
# (Brezzi-Douglas-Marini) elements.

# Compile this form with FFC: ffc -l dolfin MixedPoisson.form

q = 1

BDM = FiniteElement("Brezzi-Douglas-Marini", "triangle", q)
DG  = FiniteElement("Discontinuous Lagrange", "triangle", q - 1)

mixed_element = BDM + DG

(tau, w) = TestFunctions(mixed_element)
(sigma, u) = TrialFunctions(mixed_element)

f = Function(DG)

a = (dot(tau, sigma) - div(tau)*u + w*div(sigma))*dx
L = w*f*dx