v2.3

v2.3.2

Fixed two bugs in point-wise LU.
Solver changes:
- Refactored solver classes (no interface changes); added TRichardson to replace TSolver in the future.
- Fixed inconsistent computation of residual norm in solvers. Now Richardson, CG and BiCG will compute standard residual norm, while MINRES and GMRES compute preconditioned residual norm.
- Made initialisation of start vector in solver classes optional (function initialise_start_value)
Added function "diagonal" to extract diagonal of a matrix.
Added example "spectrum" to compute spectrum of graph Laplacian.

Fixed issues when solving dense matrices (used in new example for many RHSs).
Modified THiLoFreqGeomAdmCond: now maximal number of wavelengths per cluster is tested.
Refactored geometrical clustering classes and partitioning strategies, thereby fixing several issues.
C++11 changes:
- most object creating functions now return std::unique_ptr,
- replaced typedef by using,
- added iterators for TIndexSet, TNodeSet, TGraph, TProcSet (for range based for).
- Note: needs at least GCC v4.7 or equivalent!
Added parameter to algebraic clustering in C bindings to define partitioning algorithm (BFS, multi level, METIS or Scotch).
Fixed issues with progress bar during factorisation (wrong block count).
Removed BSP style comminucation functions (MPI only now).
Finished conversion to new packed_t SIMD type. Using SSE3 instead of SSE2.
Added lock to TScotchAlgPartStrat because Scotch is not multi thread safe.

Removing implicit reordering of unknowns during matrix-vector multiplication to fix inconsistent behaviour. Please use permutations from cluster trees or 𝓗-matrices to reorder vectors or TPermMatrix to represent permuted matrices instead.
Speedup improvements for matrix inversion. Triangular inversion and matrix multiplication available in standard user interface.
Import/export from/to CCS/CRS matrices simplified.
Simplified (and faster) mutex wrapper.
Several C++11 changes.

Removing reference counters in BLAS interface due to major performance issue on multi-core (-socket) systems. See BLAS/LAPACK Interface on how to use the modified interface (and avoid errors).
New, scalable matrix-vector multiplication implemented.
Using generic datatype for SIMD instructions, thereby enabling generic SIMD algorithms, e.g. for BEM kernels, and fast adoptation of new SIMD instructions, e.g. AVX2.
Started to use block-wise operations if dense matrices are combined with blocked matrices (e.g. during matrix multiplication) instead of vector operations.
Removed TVirtualVector (replaced by TScalarVector).
Fixed issue with MatrixMarket format (leading whitespaces).

Major Changes
- Switched from OpenMP to Threading Building Blocks as interface to shared memory parallelism, thereby also changing most algorithms to task-based parallelism.
- Reducing dependency on external libraries by using C++11 features. Also replacing some classes by default C++ versions (finally removing old code).
- Alternative, non-recursive, level-wise ℋ-LU factorisation based on explicit block dependencies, which provides far better speedup on many-core systems, e.g. Intel MIC architecture.
- New ℋ-LU factorisation algorithm also applicable in distributed environments, yielding better load-balancing (albeit with limited speedup).
- Added support for multiple CPUs to many algorithms, e.g. in clustering, norm computations, matrix-vector multiplication and solves, ℋ²-convertion.
Minor Changes
- Optimised BEM kernels for Intel MIC architecture.
- Introduced TLinearOperator for operators not supporting TMatrix functionality, e.g. factorised matrices.
- HLIBpro file format changed due to internal changes and due to some bugs in the format. However, backward read compatibility for most files written with earlier versions is kept.
- Added Support for Cairo library, thereby providing PDF output.
And of course: many smaller feature upgrades and bug fixes.