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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 | # Copyright (C) 2006-2009 Anders Logg and Marie Rognes
#
# This file is part of UFL.
#
# UFL is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# UFL is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with UFL. If not, see <http://www.gnu.org/licenses/>.
#
# Modified by Martin Sandve Alnes, 2009
#
# Last changed: 2009-01-12
#
# 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.
#
cell = triangle
BDM1 = FiniteElement("Brezzi-Douglas-Marini", cell, 1)
DG0 = FiniteElement("Discontinuous Lagrange", cell, 0)
element = BDM1 * DG0
(tau, w) = TestFunctions(element)
(sigma, u) = TrialFunctions(element)
f = Coefficient(DG0)
a = (dot(tau, sigma) - div(tau)*u + w*div(sigma))*dx
L = w*f*dx
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