mixedpoisson.form

利用C

# Copyright (C) 2006-2007 Anders Logg ([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

(v, w) = TestFunctions(mixed_element)
(q, u) = TrialFunctions(mixed_element)
f = Function(DG)

a = (dot(v, q) - div(v)*u + w*div(q))*dx
L = w*f*dx