def perform_condensation(full_problem, reduced_problem, dim):
"""
Obtain reduced matrix and rhs.
"""
A = full_problem.lhs
rhs = full_problem.rhs
to_be_eliminated = SC.dofs_of_dimension(full_problem.grid(), A, dim)
a_reduced, rhs_reduced, _, _, _ = SC.eliminate_dofs(
A, rhs, to_be_eliminated)
reduced_problem.lhs = a_reduced
reduced_problem.rhs = rhs_reduced
def solve(self, max_direct=40000, callback=False, **kwargs):
"""
This is an adaption of the elliptic solver to the Schur complement
elimination. The only change can be found in the if self.el statement.
"""
# Discretize
tic = time.time()
logger.info("Discretize")
self.lhs, self.rhs = self.reassemble()
if self.el:
to_be_eliminated = SC.dofs_of_dimension(other.grid(), other.lhs,
eldim)
self.lhs, self.rhs, _, _, _ = SC.eliminate_dofs(
other.lhs, other.rhs, to_be_eliminated)
logger.info("Done. Elapsed time " + str(time.time() - tic))
# Solve
tic = time.time()
ls = LSFactory()
if self.rhs.size < max_direct:
logger.info("Solve linear system using direct solver")
self.x = ls.direct(self.lhs, self.rhs)
else:
logger.info("Solve linear system using GMRES")
precond = self._setup_preconditioner()
# precond = ls.ilu(self.lhs)
slv = ls.gmres(self.lhs)
self.x, info = slv(
self.rhs,
M=precond,
callback=callback,
maxiter=10000,
restart=1500,
tol=1e-8,
)
if info == 0:
logger.info("GMRES succeeded.")
else:
logger.error("GMRES failed with status " + str(info))
logger.info("Done. Elapsed time " + str(time.time() - tic))
return self.x