xref: /petsc/doc/changes/39.md (revision b11d9968bc79904c690b122f9399be46447eb113)

# Changes: 3.9

```{rubric} General:
```

- The scripts in \$PETSC_DIR/bin are now in \$PETSC_DIR/lib/petsc/bin
- PetscStrncat() renamed to PetscStrlcat() now takes the length of
  the original allocated space in the string instead of the part
  left after strings have been copied or concatenated in
- CUDA and ViennaCL as GPU backends can now also be used with the
  release version (no need to use the main branch).

```{rubric} Configure/Build:
```

- Option --with-cuda-arch is removed. Use CUDAFLAGS to directly
  specify relevant nvcc option [for ex: CUDAFLAGS=-arch=sm_20]
- Added --with-avx512-kernels to specify that hand-coded kernels
  using AVX-512 intrinsics should be used when available. Currently
  defaults to off.

```{rubric} IS:
```

```{rubric} PetscDraw:
```

```{rubric} PF:
```

```{rubric} Vec:
```

- Added VECNODE type. Vector uses on-node shared memory to store its
  entries.

```{rubric} VecScatter:
```

- VecScatter becomes a PETSc object. Existing vecscatters have types
  VECSCATTERSEQ, VECSCATTERMPI1.
- Added VECSCATTERMPI3. It stores vector ghost values to the on-node
  shared memory.
- Added VECSCATTERMPI3NODE. It works on vectors of type VECNODE.

```{rubric} PetscSection:
```

```{rubric} Mat:
```

- Added MatShellTestMultTranspose() and MatShellTestMult() for
  checking if user provided MATSHELL matches the Jacobian of a given
  function computed with differencing.
- MatSolverPackage is replaced with MatSolverType.
- mat_solver_package is replaced with mat_solver_type in options,
  e.g. `-pc_factor_mat_solver_type` should be used instead of
  `-pc_factor_mat_solver_package`.
- MatShellSetOperation() and MatShellGetOperation() can now only be
  used for MATSHELL matrices, use MatSetOperation() and
  MatGetOperation() to set an operation for any matrix type.
- Added MatMumpsGetInverse().
- MatMult() for the MATAIJ type has been optimized using AVX-512
  intrinsics; must be enabled at configure time.
- Added a new Mat type MATSELL, featuring a fast MatMult() kernel on
  AVX-512 architecture such as KNL and Skylake.
- Added support for additional MKL sparse BLAS operations in
  MATAIJMKL: MatMatMult(), MatTransposeMatMult(), MatPtAP()
  (symmetric A only). MKL version 18, update 2 or later is required
  for MatPtAP()/MatPtAPNumeric() and MatMatMultNumeric().
- Added MatGetInertia() for SuperLU_DIST interface.

```{rubric} PC:
```

- Added -pc_mg_distinct_smoothup and PCMGSetDistinctSmoothUp() so
  that one can control the down and up smoothers options separately
  from the options database
- Removed -pc_mg_smoothup and -pc_mg_smoothdown and
  PCMGSetNumberSmoothUp() and PCMGSetNumberSmoothDown(). Instead,
  configure the solvers on the levels with -mg_levels_ksp_max_it n.
  If separate numbers of smoothing steps are required for up and
  down smoothers, use -pc_mg_distinct_smoothup -mg_levels_ksp_max_it
  n -mg_levels_up_ksp_max_it m.
- Added PCCHOLESKY to SuperLU_DIST interface.

```{rubric} KSP:
```

```{rubric} SNES:
```

- Removed SNESHasDM() because there is always a DM in SNES.
- The SNESType of SNESTEST has been removed, the testing code can
  now be accessed with the options -snes_test_jacobian,
  -snes_test_jacobian_display -snes_test_jacobian_display_threshold
  and is called each time SNES computes a new Jacobian.

```{rubric} SNESLineSearch:
```

```{rubric} TS:
```

- Added TSRHSJacobianTestTranspose() and TSRHSJacobianTest()
  checking if user provide MATSHELL Jacobian with TSSetRHSJacobian()
  matches the Jacobian of the function provided to
  TSSetRHSFunction() computed with finite differencing. Command line
  options -ts_rhs_jacobian_test_mult_transpose
  -mat_shell_test_mult_transpose_view and -ts_rhs_jacobian_test_mult
  -mat_shell_test_mult_view.
- Added -ts_trajectory_dirname and -ts_trajectory_filetemplate to
  allow users to specify the folder name and file name template for
  disk checkpoints.

```{rubric} TAO:
```

- Changed TaoDefaultMonitor() to TaoMonitorDefault() to match other
  PETSc default monitor names, also now print with the same format
  as other monitors %3D Tao ....
- Added VecLock{Push|Pop} calls around user callbacks; use of
  VecGetArray in user callbacks is now prohibited.
- Added default matrix-free finite-differencing implementation for
  Hessian MatMult with TaoDefaultComputeHessianMFFD(). Can be
  selected with -tao_mf_hessian at command line.
- Added Projected Gradient Descent (PGD) and Bounded Nonlinear
  Conjugate Gradient (BNCG) algorithms for bound constrained
  problems.
- Improved support for recycling BFGS correction vectors between
  subsequent TaoSolve() calls for the unconstrained LMVM algorithm.
  Can be enabled using -tao_lmm_recycle at command line.
- Convergence tests for all algorithms are separated out of
  TaoMonitor() calls.

```{rubric} DM/DA:
```

```{rubric} DMPlex:
```

- Deprecate DMGetDefaultSection() in favor of DMGetSection()
- Deprecate DMSetDefaultSection() in favor of DMSetSection()
- Deprecate DMGetDefaultGlobalSection() in favor of
  DMGetGlobalSection()
- Deprecate DMSetDefaultGlobalSection() in favor of
  DMSetGlobalSection()

```{rubric} PetscViewer:
```

- PetscViewerVTKFWrite() now takes a MPI_Datatype instead of a
  PetscDataType argument.

```{rubric} DMNetwork:
```

- DMNetworkGetComponentDataArray and DMNetworkGetComponentTypeOffset
  are no longer available. Use DMNetworkGetComponent instead.
- Added support for sub-dmnetworks.

```{rubric} SYS:
```

- PetscPClose() no longer returns error code from pclose() because
  some systems cannot reliably deliver it
- PetscPopUpSelect() has been removed.

```{rubric} AO:
```

```{rubric} Sieve:
```

```{rubric} Fortran:
```

- The F90Array routines now take a MPI_Datatype argument instead of
  a PetscDataType. This should not affect user code.