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# Hedge - the Hybrid'n'Easy DG Environment
# Copyright (C) 2007 Andreas Kloeckner
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
from __future__ import division
import numpy
import numpy.linalg as la
from hedge.tools import Reflection, Rotation
class ResidualPrinter:
def __init__(self, compute_resid=None):
self.count = 0
self.compute_resid = compute_resid
def __call__(self, cur_sol):
import sys
if cur_sol is not None:
if self.count % 20 == 0:
sys.stdout.write("IT %8d %g \r" % (
self.count, la.norm(self.compute_resid(cur_sol))))
else:
sys.stdout.write("IT %8d \r" % self.count)
self.count += 1
sys.stdout.flush()
def main(write_output=True):
from hedge.data import GivenFunction, ConstantGivenFunction
from hedge.backends import guess_run_context
rcon = guess_run_context()
dim = 2
def boundary_tagger(fvi, el, fn, points):
from math import atan2, pi
normal = el.face_normals[fn]
if -90/180*pi < atan2(normal[1], normal[0]) < 90/180*pi:
return ["neumann"]
else:
return ["dirichlet"]
def dirichlet_boundary_tagger(fvi, el, fn, points):
return ["dirichlet"]
if dim == 2:
if rcon.is_head_rank:
from hedge.mesh.generator import make_disk_mesh
mesh = make_disk_mesh(r=0.5,
boundary_tagger=dirichlet_boundary_tagger,
max_area=1e-3)
elif dim == 3:
if rcon.is_head_rank:
from hedge.mesh.generator import make_ball_mesh
mesh = make_ball_mesh(max_volume=0.0001,
boundary_tagger=lambda fvi, el, fn, points:
["dirichlet"])
else:
raise RuntimeError, "bad number of dimensions"
if rcon.is_head_rank:
print "%d elements" % len(mesh.elements)
mesh_data = rcon.distribute_mesh(mesh)
else:
mesh_data = rcon.receive_mesh()
discr = rcon.make_discretization(mesh_data, order=5,
debug=[])
def dirichlet_bc(x, el):
from math import sin
return sin(10*x[0])
def rhs_c(x, el):
if la.norm(x) < 0.1:
return 1000
else:
return 0
def my_diff_tensor():
result = numpy.eye(dim)
result[0,0] = 0.1
return result
try:
from hedge.models.poisson import (
PoissonOperator,
HelmholtzOperator)
from hedge.second_order import \
IPDGSecondDerivative, LDGSecondDerivative, \
StabilizedCentralSecondDerivative
k = 1
from hedge.mesh import TAG_NONE, TAG_ALL
op = HelmholtzOperator(k, discr.dimensions,
#diffusion_tensor=my_diff_tensor(),
#dirichlet_tag="dirichlet",
#neumann_tag="neumann",
dirichlet_tag=TAG_ALL,
neumann_tag=TAG_NONE,
#dirichlet_tag=TAG_ALL,
#neumann_tag=TAG_NONE,
#dirichlet_bc=GivenFunction(dirichlet_bc),
dirichlet_bc=ConstantGivenFunction(0),
neumann_bc=ConstantGivenFunction(-10),
scheme=StabilizedCentralSecondDerivative(),
#scheme=LDGSecondDerivative(),
#scheme=IPDGSecondDerivative(),
)
bound_op = op.bind(discr)
if False:
from hedge.iterative import parallel_cg
u = -parallel_cg(rcon, -bound_op,
bound_op.prepare_rhs(discr.interpolate_volume_function(rhs_c)),
debug=20, tol=5e-4,
dot=discr.nodewise_dot_product,
x=discr.volume_zeros())
else:
rhs = bound_op.prepare_rhs(discr.interpolate_volume_function(rhs_c))
def compute_resid(x):
return bound_op(x)-rhs
from scipy.sparse.linalg import minres, LinearOperator
u, info = minres(
LinearOperator(
(len(discr), len(discr)),
matvec=bound_op, dtype=bound_op.dtype),
rhs,
callback=ResidualPrinter(compute_resid),
tol=1e-5)
print
if info != 0:
raise RuntimeError("gmres reported error %d" % info)
print "finished gmres"
print la.norm(bound_op(u)-rhs)/la.norm(rhs)
if write_output:
from hedge.visualization import SiloVisualizer, VtkVisualizer
vis = VtkVisualizer(discr, rcon)
visf = vis.make_file("fld")
vis.add_data(visf, [ ("sol", discr.convert_volume(u, kind="numpy")), ])
visf.close()
finally:
discr.close()
if __name__ == "__main__":
main()