block_diag_ilu
block_diag_ilu is an open source C++ single header-file implementation of an
incomplete LU decomposition routine suitable for diagonally dominant (square) block diagonal
matrices with sub- and super diagonals of small magnitude. It is useful for
preconditioning linear systems. The use-case in mind is for integrating discretized PDEs of mixed
chemical kinetics / diffusion problems where the diffusion process may be accurately
considered a mild perturbation.
A picture is worth a thousand words, so if your matrix looks anything like this:
then its LU decomposition then looks like this:
then block_diag_ilu should be able to save quite a bit of time when
solving linear systems approximately, e.g. for preconditioning.
Conditional compilation
The following macros affect the compilation:
| Macro name | Action (when defined) | Default |
|---|---|---|
| NDEBUG | use std::unique_ptr instead of
std::vector as underlying data structure. |
undefined |
| BLOCK_DIAG_ILUT_WITH_OPENMP | factorize blocks in parallel. Set the environment variable BLOCK_DIAG_ILU_NUM_THREADS to control number of threads. | undefined |
setup.py will set these when envinronment variables with those are set to "1".
License
The source code is Open Source and is released under the very permissive
"simplified (2-clause) BSD license". See LICENSE.txt for further details.
Contributors are welcome to suggest improvements at https://github.com/chemreac/block_diag_ilu
Author
- Björn Dahlgren, contact:
-
- gmail adress: bjodah
- kth.se adress: bda
