============
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.