Document addition of PetscRegressor and PETSCREGRESSORLINEAR in dev.md

MatLMVM: Complete rework of internals to use LMBasis and LMProducts

I don't think there is a good way to break this up into smaller commits: once I
use LMBasis and LMProducts in Mat_LMVM, all of the

MatLMVM: Complete rework of internals to use LMBasis and LMProducts

I don't think there is a good way to break this up into smaller commits: once I
use LMBasis and LMProducts in Mat_LMVM, all of the implementations that depend on
it are broken until they are changed to also use these new objects. It is probably
better to review all of the MatLMVM implementations (except for denseqn) as new code
rather than trying to review using a diff tool.

This rework achieves:

- Implementations of three classes of algorithms for limitd memory quasi-Newton updates
- MAT_LMVM_MULT_RECURSIVE: Recursive, level 1 BLAS algorithms that closely match
the typical way the methods are presented mathematically.
- MAT_LMVM_MULT_DENSE: level 2 BLAS algorithms that, when possible,
avoid any need for recomputation when the reference Jacobian J0 changes.
- MAT_LMVM_MULT_COMPACT_DENSE: level 2 BLAS algorithms that construct rank-m (or rank-2m)
update representations of the operators, for the best-performance on MatMult() and MatSolve(),
but at the cost of additional setup, and requiring more recomputation when J0 changes
than MAT_LMVM_MULT_DENSE
- Every quasi-Newton method has a dual method (e.g. BFGS and DFP): we exploit this duality
to use only one code path for a dual pair, reducing the numer of implementaitons to maintain
- Special handling of the case J0 = gamma * I, avoiding products that are unnecessary in this case
- Instead of including a MatLMVMDiagBrdn as the J0 matrix when J0 is
variable (which means that both B and J0 of basis vectors to maintain),
a SymBroydenRescale object is shared by MatLMVMDiagBrdn and other formats that use rescaling
- Improved correctness of when internal products need to be recomputed: if the user externally
changes J0, this will be detected

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Mat: Improve the usability of constantdiagonal and diagonal matrices

Mat_ConstantDiagonal: Add MatConstantDiagonalGetConstant() and implement conjugate and transpose

Mat_Diagonal: Add missing setra

Mat: Improve the usability of constantdiagonal and diagonal matrices

Mat_ConstantDiagonal: Add MatConstantDiagonalGetConstant() and implement conjugate and transpose

Mat_Diagonal: Add missing setrandom, conjugate, and transpose methods

MatView: Don't print MatInfo for constantdiagonal or diagonal matrices

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doc: add petsc discord server info to 2025 meeting.

Merge remote-tracking branch 'origin/release'

Merge branch 'barry/2025-04-06/docs-mv-tutorials-gitlab/release' into 'release'

Move the old tutorial slides from https://www.mcs.anl.gov/petsc/documentation/tutorials to https://petsc.gitlab.io/tut

Merge branch 'barry/2025-04-06/docs-mv-tutorials-gitlab/release' into 'release'

Move the old tutorial slides from https://www.mcs.anl.gov/petsc/documentation/tutorials to https://petsc.gitlab.io/tutorials

See merge request petsc/petsc!8303

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Add initial version PetscRegressor, part of the planned machine learning (ML) toolkit

Co-authored-by: Mr. Hong Zhang <hongzhang@anl.gov>
Co-authored-by: Hansol Suh <hsuh@anl.gov>
Co-authored-by: Bar

Add initial version PetscRegressor, part of the planned machine learning (ML) toolkit

Co-authored-by: Mr. Hong Zhang <hongzhang@anl.gov>
Co-authored-by: Hansol Suh <hsuh@anl.gov>
Co-authored-by: Barry Smith <bsmith@petsc.dev>
Co-authored-by: Toby Isaac <toby.isaac@gmail.com>
Co-authored-by: Satish Balay <balay@mcs.anl.gov>

Mr. Hong Zhang developed the petsc4py interface and examples.
Hansol Suh provided extensive help with updating the code to the latest PETSc coding guidelines and APIs, some documentation development, getting documentation to build correctly, getting new tests into the test harness, and numerous big fixes plus minor changes.
Barry Smith provided extensive feedback and code to get the Fortran interfaces and documentation build working.
Toby Isaac provided a fix to prevent breakage with complex-arithmetic builds.
Satish Balay provided important help with fixing builds.

Thanks-to: Pierre Jolivet <pierre@joliv.et>
Thanks-to: Jed Brown <jed@jedbrown.org>
Thanks-to: Jose Roman <jroman@dsic.upv.es>
Thanks-to: Stefano Zampini <stefano.zampini@gmail.com>

Pierre, Jed, Jose, and Stefano provided extremely helpful feedback and suggestions during the merge review process.

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Move the old tutorial slides from https://www.mcs.anl.gov/petsc/documentation/tutorials to https://petsc.gitlab.io/tutorials

Merge remote-tracking branch 'origin/release'

Merge branch 'jczhang/2025-04-08/update-petsc-2025' into 'release'

Update petsc-2025

See merge request petsc/petsc!8292

Update petsc-2025

Move changes/dev.rst to changes/dev.md

Merge remote-tracking branch 'origin/release'

move last of the doc rst files over to md files

Bib: Add refs

Plex: Now set coordFunc separately from DMPlexRemapGeometry()
- Add DMPlexGetCoordinateMap() and DMPlexSetCoordinateMap()
- Moved function pointer types to petscdstypes.h

Merge remote-tracking branch 'origin/release'

Doc Tao: fixed the typo in EvaluateHessian description

Fix wrong case for PETSc

Plex: Add ability to save a mesh transform

Improve documentation of the PETSc repositories for images, annual meetings, and datafiles

Edit 323.rst

revert sources to dev
- reset PETSC_VERSION_RELEASE
- reset doc/changes/dev.rst

release: set petsc v3.23.0 strings

Merge remote-tracking branch 'origin/release'