# Changes: 2.0.29

## Changes

(See [Features] below)

```{rubric} General:
```

```{rubric} AO (Application Orderings):
```

```{rubric} TS (Timestepping Solvers):
```

```{rubric} SNES (Nonlinear Solvers):
```

- The second argument to MatSNESMFSetType() is now a MatSNESMFType,
  rather than a char\*. This should not affect any user code. Current
  built in choices are MATSNESMF_DEFAULT "default" and MATSNESMF_WP
  "wp"
- SNESGetJacobian() now has an additional optional final argument
  that can return the function pointer
- SNESGetFunction() now has an additional optional final argument
  that can return the function pointer

```{rubric} SLES (Linear Solvers):
```

```{rubric} KSP (Krylov Subspace Methods):
```

```{rubric} PC (Preconditioners):
```

- PCILUSetReuseFill() changed to PCILUDTSetReuseFill() and
  -pc_ilu_reuse_fill changed to -pc_iludt_reuse_fill Note that
  currently these functions don't work.
- PCNullSpaceXXX changed to MatNullSpaceXXX except for
  PCNullSpaceAttach()
- MGSetLevels() now takes an additional optional final argument that
  is an array of communicators to use on the SLES on each level

```{rubric} MAT (Matrices):
```

- Changed MatDiagonalShift(Mat,Vec) to
  MatDiagonalSet(Mat,Vec,InsertMode);
- Dropped the second to last argument to MatCreateRowbs()
- -mat_ordering_type now should be either -pc_ilu_mat_ordering_type,
  -pc_lu_mat_ordering_type, -pc_icc_mat_ordering_type or
  -pc_cholesky_mat_ordering_type

```{rubric} DA (Distributed Arrays):
```

```{rubric} VEC (Vectors):
```

```{rubric} IS (Index Sets):
```

- ISEqual() now is collective and returns true only if each
  processor has the same indices
- ISGetSize() now returns global parallel size, ISGetLocalSize()
  returns local size

```{rubric} General:
```

- All include files like mat.h vec.h sles.h snes.h ts.h etc are now
  changed to petscmat.h petscvec.h petscsles.h petscsnes.h petscts.h

```{rubric} Draw (Graphics):
```

```{rubric} Viewers:
```

```{rubric} System:
```

- FListDestroy now takes FList * instead of FList

```{rubric} Error Handling:
```

```{rubric} Event Logging:
```

- PLogEventBegin(), PLogEventEnd(), PLogFlops(),
  PLogEventBarrierBegin() and PLogEventBarrierEnd() now return error
  codes.

```{rubric} Fortran Interface:
```

## Features

(See [Changes] above)

```{rubric} General:
```

```{rubric} AO (Application Orderings):
```

```{rubric} TS (Timestepping Solvers):
```

```{rubric} SNES (Nonlinear Solvers):
```

```{rubric} SLES (Linear Solvers):
```

```{rubric} KSP (Krylov Subspace Methods):
```

- Minres solver contributed by: Robert Scheichl:
  <mailto:maprs@maths.bath.ac.uk>
- SYMMLQ solver contributed by Hong Zhang

```{rubric} PC (Preconditioners):
```

- ICC(k) and Cholesky() preconditioners are now available for the
  new SeqSBAIJ matrices.
- added -pc_ilu_damping and -pc_lu_damping, PCILUSetDamping(),
  PCLUSetDamping() for handling singular or matrices that generate a
  zero pivot.
- Added DAMGCreate() etc to help easily write parallel multigrid
  codes that use rectangular grids
- Paulo Goldfeld contributed new PCType of nn, a version of Mandel's
  balancing Neumann-Neumann preconditioner, see
  src/contrib/oberman/laplacian_q1 for an example of its use

```{rubric} MAT (Matrices):
```

- added new matrix types SeqSBAIJ and MPISBAIJ for symmetric
  matrices. These store only the upper triangular portion of the
  matrix. We also provide ICC(k) and Cholesky factorization
  (currently only for block size of 1) for the SeqSBAIJ matrices
- augmented the SeqAIJ matrices to support -mat_aij_matlab that
  causes the matrices to use the MATLAB engine for sparse LU, and
  ILUDT factorization and solves. Which have pivoting and thus are
  more robust than PETSc's default.

```{rubric} DA (Distributed Arrays):
```

- added -da_noao for DACreateXXX() makes them more scalable, but
  cannot use the natural numbering DA routines with this option.
- Added DAMGCreate() etc to help easily write parallel multigrid
  codes that use rectangular grids

```{rubric} VEC (Vectors):
```

```{rubric} IS (Index Sets):
```

```{rubric} PF:
```

- added the type PFMATLAB with -pf_type matlab -pf_matlab
  matlab_commands

```{rubric} Draw (Graphics):
```

```{rubric} Viewers:
```

```{rubric} System:
```

- Add PetscMatlabEngineCreate() which allows calling Matlab
  functions from PETSc on each processor. Good for graphics or
  numerical routines that PETSc does not have. for example for the
  local evaluation of the parallel nonlinear function required for
  SNES; see src/snes/examples/tutorials/ex5m.c. This functionality
  is accessed via the commands
  PetscMatlabEngineCreate(),Put(),Get(),Evaluate() and Destroy() It
  even imports the MATLAB flop counts correctly. Obviously you need
  enough MATLAB licenses for each node. Note: MATLAB itself is not
  directly doing any parallel computing.
- added PetscSetHelpVersionFunctions() for developers of other
  libraries that use PETSc.
- added PetscPoUpSelect(), see src/sys/examples/tests/ex15.c
- added int PetscShowMemoryUsage(Viewer viewer,char \*message)
- added PreLoadBegin(), PreLoadStage() and PreLoadEnd() to simplify
  getting accurate timings by peloading. See
  src/snes/examples/tutorials/ex10.c
- added PetscSynchronizedFGets()

```{rubric} Error Handling:
```

```{rubric} Event Logging:
```

```{rubric} Fortran Interface:
```
