Docs: change Developers Note to Developer Note

Merge branch 'jose/matproduct-getalgorithm' into 'main'

Add missing interface function MatProductGetAlgorithm()

See merge request petsc/petsc!7225

Add missing interface function MatProductGetAlgorithm()

Merge remote-tracking branch 'origin/release'

Merge branch 'barry/2024-01-04/fix-includes-man-pages/release' into 'release'

Barry/2024 01 04/fix includes man pages/release

See merge request petsc/petsc!7165

Fix manual page formating in include directory

Merge remote-tracking branch 'origin/release'

Merge branch 'barry/2023-11-20/docs-manpage-minor-work/release' into 'release'

Minor work on manual pages (in include directory)

See merge request petsc/petsc!7042

Minor work on manual pages (in include directory)

Merge remote-tracking branch 'origin/release'

Merge branch 'barry/2023-11-13/make-public-matheaderreplace/release' into 'release'

Make MatHeaderReplace() docs and Fortran interface for advanced users

See merge request petsc/petsc!7015

Make MatHeaderReplace() docs and Fortran interface for advanced users

Reported-by: Henrik Büsing <Henrik.Buesing@fgh-ma.de>

Merge branch 'adams/gamg-graph-bs-index' into 'main'

GAMG: Add option to create graph for bs>1 mat with index, or array of indices, in block entries

See merge request petsc/petsc!6933

GAMG: Add option to create graph for bs>1 mat with index, or array of indices, in block entries

Merge branch 'barry/2023-07-30/doc-better-blas-thread-usage' into 'main'

Start of PETSc benchmarking object

See merge request petsc/petsc!6772

Add PetscBench with implementation based on HPL

Merge remote-tracking branch 'origin/release'

Merge branch 'barry/2023-10-25/fix-offdiagonal/release' into 'release'

Fix use of offdiagonal to off-diagonal

See merge request petsc/petsc!6962

Fix use of offdiagonal to off-diagonal

Merge remote-tracking branch 'origin/release'

Merge branch 'prj--release-patch-45075' into 'release'

Update petscmat.h

See merge request petsc/petsc!6939

Update petscmat.h

Merge branch 'strumpack' into 'main'

Update the interface to STRUMPACK

See merge request petsc/petsc!6819

Update the interface to STRUMPACK

STRUMPACK provides a sparse direct solver (but unlike fi SuperLU, it is based on the multifrontal method). STRUMPACK also provides preconditioners based on approxim

Update the interface to STRUMPACK

STRUMPACK provides a sparse direct solver (but unlike fi SuperLU, it is based on the multifrontal method). STRUMPACK also provides preconditioners based on approximate multifrontal LU factorization. In the precoditioners larger dense blocks in the sparse LU factors are compressed using rank-structured matrix approximations (or using lossy/lossless compression using the ZFP library).

See https://github.com/pghysels/STRUMPACK https://portal.nersc.gov/project/sparse/strumpack/

This commit adds different preconditioning options. Previously only the HSS (hierarchically Semi-Separable) format was supported. Now we also have BLR (Block Low Rank), HODLR (Hierarchically Off-Diagonal) with the option to replace low-rank with butterfly, Lossy and Lossless compression (through ZFP). The new methods work considerably better than the older HSS code. When using

-pc_type lu -pc_factor_mat_solver_type strumpack

the solver behaves as a direct solver. When using

-pc_type ilu -pc_factor_mat_solver_type strumpack

it will work as a preconditioner, using BLR compression. This should be a robust preconditioner for a wide range of problems. One can tune the compression tolerance, and the minimum block (separator) size for compression using:

-mat_strumpack_compression_rel_tol 1e-3 -mat_strumpack_compression_min_sep_size 500

You can also select the compression type explicitly

-pc_type ilu -pc_factor_mat_solver_type strumpack -mat_strumpack_compression LOSSY

For now we recommend BLR, as it seems to work best, and does not require additional external dependencies (it is also what MUMPS implements).

Also updates the test src/ksp/ksp/tutorials/ex52.c.

Also adds support for the solve with multiple RHS.

Also adds an option for the GEOMETRIC fill-reducing ordering which performs nested dissection on a regular nx x ny x nz grid with nc degrees of freedom per grid-point and a stencil (potentially a wider stencil). It is assumed that the matrix is in the natural (lexicographical?) ordering. This can make reordering much faster for regular grid problems.

Also adds installation scripts STRUMPACK dependencies SLATE, ZFP and ButterflyPACK. SLATE is a scalapack replacement with GPU capabilities. ZFP is used for floating point compression. ButterflyPACK is used for the HODLR and HODBF compression schemes.

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Merge branch 'jacobf/2023-08-17/header-guard-check' into 'main'

Check header guards

See merge request petsc/petsc!6822