Add custom fortran stub for MatCreateNest()

Otherwise PETSC_NULL_IS_ARRAY cannot be used for is_row, is_col

Mat: Fix and improve the performance of dense matrix multiplication

Mat: Add MATDENSEFROMVECTYPE constructor type

Now in a tests set you can do

```
testset:
args: -mat_type densefromvectype

Mat: Fix and improve the performance of dense matrix multiplication

Mat: Add MATDENSEFROMVECTYPE constructor type

Now in a tests set you can do

```
testset:
args: -mat_type densefromvectype
test: test_cuda
requires: cuda
args: -vec_type veccuda
test: test_hip
requires: hip
args: -vec_type vechip
```

(This assumes that you call `MatSetVecType()` before you call
`MatSetFromOptions()`)

Mat_MPIDense: Cache offsets of MatDenseGetSubMatrix() to avoid communication in more cases

Mat: Add missing implementations for internal "MatMultColumnRange()" interface

Mat_MPIDense: Fix the zeroing of buffers in multiplication routines

Mat_MPIDense: Add optimization of MatMatMult routines when all columns are owned by rank 0

The communication for intermediate buffers can be handled with allreduce / bcast operations,
but we use the PetscSF matvec context instead of MPI routines directly so that we will
use gpu-aware MPI if possible.

show more ...

Mat: need to access the mataij value array via accessors to maintain host/device sync state

Reported-by: Steven Dargaville <dargaville.steven@gmail.com>

Fix wrong case for PETSc

MatProduct: fix unsafe cases for block size propagation

Add test from Pierre

Add Fortran support for MatGet/RestoreRow

Reported-by: Steven Dargaville

Merge branch 'stevendargaville/mat-kokkoscreatedevice' into 'main'

Added new API calls to allow kokkos matrices to be built with no host preallocation

See merge request petsc/petsc!8206

Changes to allow building gpu matrices on the device.

Changed MatCreateMPIAIJWithSeqAIJ() so global sizes must be given to prevent reduction.

Changed MatCreateMPIAIJWithSeqAIJ() so B can be passed

Changes to allow building gpu matrices on the device.

Changed MatCreateMPIAIJWithSeqAIJ() so global sizes must be given to prevent reduction.

Changed MatCreateMPIAIJWithSeqAIJ() so B can be passed in with local indices, hence no compactification occurs.

Added MatCreateSeqAIJKokkosWithKokkosViews() which creates a Mat with no preallocation on the host.

Added test that checks building kokkos matrices without any host preallocation

show more ...

Fortran 90: fully embrace After 34 years!

- deprecate use of 'F90' in Fortran function names
- use Fortran pointers when appropriate
- the new Fortran API is not backward compatible with previous ve

Fortran 90: fully embrace After 34 years!

- deprecate use of 'F90' in Fortran function names
- use Fortran pointers when appropriate
- the new Fortran API is not backward compatible with previous versions!
- also clean up inconsistent PETSc code detected by new Fortran generation tools
- drop use of bfort
- automatically generate all the Fortran PETSc objects, enums etc from the include files
- generate most of the Fortran interface definitions and functions from the source code
- simplify the number and organization of Fortran modules

Co-authored-by: Jose E. Roman <jroman@dsic.upv.es>

show more ...

Merge remote-tracking branch 'origin/release'

Fix bug in our FFTW interface that could produce completely incorrect results for any of the nontrivial FFTW plans.

Reported-by: Satish Balay

make: add explicit '% : %.c' target so that LINK.c target is in sync with LINK.F target '% : %.F90'

with multiple source compile into a singe binary:
- fixes Fortran example build: currently broken,

make: add explicit '% : %.c' target so that LINK.c target is in sync with LINK.F target '% : %.F90'

with multiple source compile into a singe binary:
- fixes Fortran example build: currently broken, due to duplicate obj-files in link command
- can now use consitent obj file dependencies irrespective of C-main or Fortran-main sources
- cab avoid duplicate compiles of same sources [esp with SEPARATE_COMPILE_LINK=1]

show more ...

Merge remote-tracking branch 'origin/release'

Improve some manual pages in KSP/SNES

Merge remote-tracking branch 'origin/release'

Add test showing issue with MatResetPreallocation_MPIAIJ

Add a MatResetHash API

Add MatCopyHashToXAIJ() to copy hash table entries into an XAIJ matrix type

brain dead fixes for useless casts in examples

CI: enable compilation of examples in some stage-1 jobs