This patch fixes a memory leak when using AMG as a coarse level solver
for the two level method. As there was no need to store the solver as
a pointer (it was copied anyway), we now simply store it by value.

[twolevelmethod][bugfix] Copy coarse level solver for thread safety. (2nd tparam of TwolevelMethod changed!)

Previously all copies of the twolevel method used the same
coarse level solver. In the case of AMG this resulted in wrong
results as it stores internal data across several applications.
This patch now always copies the internal coarse level data.

In addition the left hand side given to AMG as a coarse level solver
is copied to use it for the post method in the constructor.

Note that the meaning of the template parameters of TwolevelMethod is
changed. Its second parameter is now the type of the coarse level
solver rather than the coarse level linear operator. The latter is
deduced from the previous now. This was needed to supportt copying of
the coarse level solver.

Previously copying of TowLevelMethod did not compile. In addition
the coarse solver was not copied as it should. This patch fixes this.

The LevelTransferPolicies have internal storage for lhs and rhs that
should be cloned in each copy to prevent overwriting values. This
patch accomplishes this.

Previously the current residual was not updated after the coarse
grid correction. This patch fixes this by storing the only the
prolongated coarse grid correction in context.lhs and updating the
accumulated update. During postsmoothing the currently residual is
updated according to context.lhs.

For the postsmmothing to work we have to reset context.lhs to 0
which still contains the update from the last presmoothing step.
This patch does this.

1. do call postsmooth instead of pre smoothing for post smoothing.
2. Prolongate coarse grid correction to correct fine level vector.
3. Changed test to use regular patches and schwarz mod that mimics
   regular smoother for better comparison.
4. Improved documentation.

Previously setting the define overwrote the flags for superlu.

With this addition it is possible to construct a twolevel method by
specifying a fine level smoother (e.g. SeqOverlappingSchwarz), a
policy for the grid transfer, and a policy for constructing the
coarse level solver.

This patch removed the tests for umfpack from dune-istl as they
are already needed in dune-common. There are modules using umfpack
that do not require dune-istl. Therefore dune-common seems to be the
more appropriate place for the test.

Arne Morten Kvarving authored 11 years ago and Markus Blatt committed 11 years ago

now the preconditioner can be used in a Dune::Preconditioner context

Dominic Kempf authored 11 years ago and Markus Blatt committed 11 years ago

This reverts commit 5336f23b950e9f1b5b8a51cdc103142ab47a779e.

This is supposed to be a temporary hack. If Umpack is available
the it is chosen of SuperLU. Otherwise SuperLU is chosen if it
is available.

Dominic Kempf authored 11 years ago and Markus Blatt committed 11 years ago

This commit contains
- a wrapper for the C library UMFPack
- tests for both CMake and autotools to find UMFPack on the system
- a unit test for UMFPack
- a new MatrixType ColCompMatrix which is a base class for a column
  compressed matrix. SuperLUMatrix now inherits from this base class.
  This way, no code is duplicated for the very similar interface in
  UMFPack.
- the SuperLU-specific part of OverlappingSchwarz code is abstracted
  to work with either SuperLU or UMFPack

This caused build errors with CMake.