# Changes: 3.25

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```{rubric} General:
```

- Change behavior of `-options_left` when set to `true`: it no longer triggers a call to `PetscOptionsView()`
- Change `$PETSC_DIR/lib/petsc/bin/petscfreesharedmemory` to `$PETSC_DIR/lib/petsc/bin/petscfreesharedmemory.sh`

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

- Make `SYCL` a `devicePackage`, i.e., builds `--with-sycl` now have `PETSC_HAVE_DEVICE` defined
- Add the option `--with-devicelanguage` to compile `PetscDevice` code using either a C or C++ compiler
- Add `Caliper`, an instrumentation and performance profiling library that can be used to profile `Hypre`.
- Add typing stubs for the Python extension module `petsc4py.PETSc`.
- Remove `--with-mumps-serial` option, rely on `--with-mpi=0`

```{rubric} Sys:
```

- Add `PetscCallHYPRE()` to check HYPRE error codes and print error messages on failure
- Add `PetscBTCountSet()` to count set bits in `PetscBT`
- Add the option `-hypre_umpire_device_pool_size <n>` to set the Umpire device memory pool size (in MiB), which is used by HYPRE and 4 Gib by default
- Change `PetscStackCallExternalVoid()` to `PetscCallExternalVoid()`
- Fix `FILE*` and fd leak in `PetscPythonFindLibraryName()` when the Python subprocess produces no output; the function now sets `*found = PETSC_FALSE` instead of raising an error

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

- Add two approaches for GPU energy monitoring:  `-log_view_gpu_energy` and `-log_view_gpu_energy_meter`
- Add API `PetscLogGpuEnergy()`, `PetscLogGpuEnergyMeter()`, `PetscLogGpuEnergyMeterBegin()` and `PetscLogGpuEnergyMeterEnd()` for GPU energy monitoring
- Remove `TAO_ObjectiveEval`, `TAO_GradientEval`, `TAO_ObjGradEval`, `TAO_HessianEval` log events; objective, gradient, objective-and-gradient, and Hessian evaluations are now logged as `TAOTERM_ObjectiveEval`, `TAOTERM_GradientEval`, `TAOTERM_ObjGradEval`, `TAOTERM_HessianEval` under `TAOTERM_CLASSID`. These log events reflect the actual user callback invoked, not the `TaoCompute*()` function called by the solver; for example, calling `TaoComputeGradient()` when only an objective-and-gradient callback is provided logs `TAOTERM_ObjGradEval`
- Add `TAO_ResidualEval` log event for `TaoComputeResidual()`; previously `TaoComputeResidual()` reused `TAO_ObjectiveEval`

```{rubric} PetscViewer:
```

- Change the final argument of `PetscViewerGLVisSetFields()` to `PetscCtxDestroyFn *`. This means the destroy function must dereference the argument before operating on it

```{rubric} PetscDraw:
```

```{rubric} AO:
```

```{rubric} IS:
```

```{rubric} VecScatter / PetscSF:
```

```{rubric} PF:
```

```{rubric} Vec:
```

- Add `VecNestGetSubVecsRead()` and `VecNestRestoreSubVecsRead()` for read-only access to subvectors
- Add `VecPointwiseSign()` and `VecSignMode`

```{rubric} PetscSection:
```

- Add `PetscSectionMigrateData()`, akin to `DMPlexDistributeData()`

```{rubric} PetscPartitioner:
```

```{rubric} Mat:
```

- Add `MatCreateDenseWithMemType()` and `MatDenseReplaceArrayWithMemType()`
- Change the `destroy()` function argument of `MatShellSetMatProductOperation()` to type `PetscCtxDestroyFn *`. This means the destroy function must dereference the argument before operating on it
- Remove `MatMissingDiagonal()`. Developers should use `MatGetDiagonalMarkers_SeqXXX()` when the functionality is needed
- Change `MatSetOption(A, MAT_HERMITIAN, PETSC_TRUE)` for `MatSBAIJ` to no longer automatically set the option `MAT_SYMMETRIC` to `PETSC_FALSE`. It is now the duty of the user to call `MatSetOption(A, MAT_SYMMETRIC, PETSC_FALSE)` if a `MatSBAIJ` is Hermitian but not symmetric
- Deprecate `-matmatmult_Bbn` in favor of `-matproduct_batch_size`
- Add `MatADot()` and `MatANorm()`
- Add `-mat_vec_type` option for `MatSetFromOptions()`

```{rubric} MatCoarsen:
```

```{rubric} PC:
```

- Add multi-precision support for MUMPS. One could use `-pc_precision <single, double>` to set the precision to be used by MUMPS, which can be different from `PetscScalar`'s precision
- Add support for MUMPS out-of-core facility with the option `-mat_mumps_ooc_tmpdir <dir>` and new functions `MatMumpsSetOocTmpDir()`, `MatMumpsGetOocTmpDir()`
- Add `PCPatchSetComputeOperatorExteriorFacets()` and `PCPatchSetComputeFunctionExteriorFacets()` to support exterior (boundary) facet integral callbacks in the patch preconditioner

```{rubric} KSP:
```

- Change `KSPSetDMActive()` to take a `KSPDMActive` argument
- Remove `KSPHPDDMPrecision` in favor of `PetscPrecision`
- Deprecate `KSPPIPEGCRSetModifyPC()`, `KSPGCRSetModifyPC()`, and `KSPFGMRESSetModifyPC()` in favor of `KSPFlexibleSetModifyPC()`
- Deprecate `KSPFGMRESModifyPCNoChange()` and `KSPFGMRESModifyPCKSP()` in favor of `KSPFlexibleModifyPCNoChange()` and `KSPFlexibleModifyPCKSP()`

```{rubric} SNES:
```

- Change the `destroy()` function argument of `SNESSetConvergenceTest()` to type `PetscCtxDestroyFn *`. This means the destroy function must dereference the argument before operating on it
- Add `SNESSetObjectiveDomainError()`
- Change `SNES_DIVERGED_FNORM_NAN` to `SNES_DIVERGED_FUNCTION_NANORINF`
- Add `SNES_DIVERGED_OBJECTIVE_NANORINF`
- Add `SNES_DIVERGED_OBJECTIVE_DOMAIN`
- Add developer functions `SNESCheckFunctionDomainError()`, `SNESLineSearchCheckFunctionDomainError()`, `SNESCheckObjectiveDomainError()`, `SNESLineSearchCheckObjectiveDomainError()`, `SNESCheckJacobianDomainError()`, and `SNESLineSearchCheckJacobianDomainError()`
- Add `SNESNewtonALSetDiagonalScaling` to allow for per-DoF scaling of solution vector when computing arc length

```{rubric} SNESLineSearch:
```

```{rubric} TS:
```

- Add `TSPseudoComputeFunction()` to get nonlinear residual while avoiding recalculation if possible
- Remove unused `TSPseudoVerifyTimeStepDefault()`
- Remove `TSPseudoComputeTimeStep()` and `TSPseudoVerifyTimeStep()`
- Change the `destroy()` function argument of `TSTrajectorySetTransform()` to type `PetscCtxDestroyFn *`. This means the destroy function must dereference the argument before operating on it
- Correct option `-ts_max_reject` to `-ts_max_step_rejections`
- Correct option `-ts_dt` to `-ts_time_step`
- Change `TSAdaptCheckStage()` to call function set by `TSAdaptSetCheckStage()` before other checks
- Fix `-ts_ssp_nstages` to `-ts_ssp_num_stages`

```{rubric} TAO:
```

- Add `TaoTerm` object to allow easily constructing and using objective functions, and their derivatives that are the sum of two or more terms. This will allow the easy implementation of Tao solvers that utilize the sum structure
- Add `TaoGetTerm()` and `TaoAddTerm()` for manipulating the objective, gradient, and Hessian evaluation of a `Tao` using `TaoTerm`
- Add `TaoGetHessianMatrices()` to get the Hessian and preconditioner matrices from a `Tao`
- Fix `TAOBRGN` such that `TAOBRGN` subsolver properly appends `TAOBRGN`'s prefix
- Change `TaoComputeResidual()` to increment a new residual evaluation counter instead of the objective function evaluation counter
- Change `-tao_view` to report residual evaluations separately and to include matrix-free finite-difference gradient evaluations in the gradient evaluation count

```{rubric} TaoTerm:
```

- Add `TAOTERMCALLBACKS` implementation of `TaoTerm` constructed from the function callbacks passed to a `Tao` object
- Add `TAOTERMSHELL` implementation of `TaoTerm` for user-defined objective routines
- Add `TAOTERMSUM` implementation of `TaoTerm` for scaled, mapped sums of terms
- Add `TAOTERMHALFL2SQUARED` implementation of `TaoTerm` for a squared-norm penalty function
- Add `TAOTERML1` implementation of `TaoTerm` for a 1-norm penalty function
- Add `TAOTERMQUADRATIC` implementation of `TaoTerm` for a quadratic penalty function
- Add finite difference utilities: `TaoTermComputeGradientFD()`, `TaoTermComputeHessianFD()`, `TaoTermCreateHessianMFFD()`, and set/get functions `TaoTermComputeGradientSetUseFD()`/`TaoTermComputeGradientGetUseFD()`, `TaoTermComputeHessianSetUseFD()`/`TaoTermComputeHessianGetUseFD()`

```{rubric} PetscRegressor:
```

```{rubric} PetscDA:
```

- Add data assimilation object `PetscDA` with two ensemble-based implementations `PETSCDAETKF` and `PETSCDALETKF` and three tutorials: Lorenz-96, traveling wave, and dam break
- Move localization `PetscDALETKFGetLocalizationMatrix()` utility out of `DMPLEX` and into `PETSCDALETKF`

```{rubric} DM:
```

- Change the final argument of `DMShellSetDestroyContext()` to `PetscCtxDestroyFn *`. This means the destroy function must dereference the argument before operating on it
- Add `DMLabelGetValueISGlobal()` to get globally consistent `IS` of values in a `DMLabel`

```{rubric} DMSwarm:
```

```{rubric} DMPlex:
```

- Add `DMPlexVecGetClosureAtDepth()`
- Add an extra communicator argument to `DMPlexFilter()` to allow extracting local meshes
- Change `verticesAdjSaved` parameter in `DMPlexCreateFromCell*Parallel*()` functions to be allocated by function rather than by user
- Add `DMPlexCreateColoring()`

```{rubric} FE/FV:
```

```{rubric} DMNetwork:
```

```{rubric} DMStag:
```

```{rubric} DT:
```

```{rubric} Fortran:
```

- Replace `./configure` option `--with-mpi-f90module-visibility` with `--with-mpi-ftn-module=<mpi or mpi_f08>`
- Add `PETSC_INT_KIND` and `PETSC_MPIINT_KIND`
- Fortran code should now use `MPIU_Comm` instead of `MPI_Comm`, and similarly for other MPI types, see section "Fortran and MPI" in the users guide
- Fortran interface definitions are now automatically generated for all functions that take context variable arguments, represented in the C source code with a type of `PetscCtx`, allowing the use of any Fortran derived type (or PETSc object) as the context
- For all PETSc functions `XXXGetYYY()` that return a context variable as an argument, represented in the C source code with an argument type of `PetscCtxRt`, a macro is generated used with `Interface_XXXGetYYY(AppCtx)` which tells the Fortran compiler that a pointer to that derived type `type(AppCtx)` is returned from the Fortran version of `XXXGetYYY()`. See src/snes/tutorials/ex5f90.F90`
