def compute_energy_norm(form, coefficient):
"""Compute the a-norm of a Coefficient given a form a.
This works simply by replacing the two Arguments
with a Coefficient on the same function space (element).
The Form returned will thus be a functional with no
Arguments, and one additional Coefficient at the
end if no coefficient has been provided.
"""
arguments = form.arguments()
parts = [arg.part() for arg in arguments]
if set(parts) - {None}:
error("compute_energy_norm cannot handle parts.")
if len(arguments) != 2:
error("Expecting bilinear form.")
v, u = arguments
U = u.ufl_function_space()
V = v.ufl_function_space()
if U != V:
error("Expecting equal finite elements for test and trial functions, got '%s' and '%s'." % (U, V))
if coefficient is None:
coefficient = Coefficient(V)
else:
if coefficient.ufl_function_space() != U:
error("Trying to compute action of form on a "
"coefficient in an incompatible element space.")
return replace(form, {u: coefficient, v: coefficient})
def compute_form_action(form, coefficient):
"""Compute the action of a form on a Coefficient.
This works simply by replacing the last Argument
with a Coefficient on the same function space (element).
The form returned will thus have one Argument less
and one additional Coefficient at the end if no
Coefficient has been provided.
"""
# TODO: Check whatever makes sense for coefficient
# Extract all arguments
arguments = form.arguments()
parts = [arg.part() for arg in arguments]
if set(parts) - {None}:
error("compute_form_action cannot handle parts.")
# Pick last argument (will be replaced)
u = arguments[-1]
fs = u.ufl_function_space()
if coefficient is None:
coefficient = Coefficient(fs)
elif coefficient.ufl_function_space() != fs:
debug("Computing action of form on a coefficient in a different function space.")
return replace(form, {u: coefficient})