# Docs: Changes: 2.1.6

CHANGES in PETSc 2.1.6

General:

- Added support for Cray X1
- Added option '-suggest' to petscarch script. It suggests some possible PETSC_ARCHes to use
- Installation instructions are rewritten

Vec:

- VecNorm now caches NORM_2
- Added VecStrideScale(), VecStrideGather(), VecStrideScatter()
- Added VecBlockNorm(),VecBlockMax(),VecBlockMin(),VecBlockScale()

Mat:

- The interface to external packages that support direct solvers has been reorganized. This is implemented using new matrix types MATSEQAIJSPOOLES, MATMPIAIJSPOOLES, MATSEQSBAIJSPOOLES, MATMPISBAIJSPOOLES, MATSUPERLU, MATSUPERLU_DIST, MATUMFPACK,MATESSL, MATLUSOL, MATAIJMUMPS, MATSBAIJMUMPS, MATDSCPACK
- Added new convenience matrix types which automatically switch between Seq and MPI implementations depending on the size of the communicator used during creation: MATAIJ, MATBAIJ, MATSBAIJ, MATMAIJ, MATDENSE, MATBDIAG
- Changed default matrix-free compute h to use WP since it uses fewer reductions
- Replace the datatypes MatLUInfo and MatILUInfo by MatFactorInfo
- Added cholesky support to SeqAIJ
- Added support for SUBSET_NONZERO_PATTERN with MatAXPY for AIJ & BAIJ
- Added MatIsSymmetric() for AIJ
- Added LDA support in SeqDense
- The ncols argument made optional in MatGetRow()
- Added MAT_KEEP_ZEROED_ROWS for MPIROWBS
- Removed -aij_oneindex support from AIJ code
- Added MatPartitioningSetPartitionWeights() - useable with ParMetis
- MatGetSubMatrices() now works for ROWBS

PC:

- Added PCICCSetDamping() or -pc_icc_damping
- Added -pc_constant_null_space
- Added PCILUSetShift() or -pc_ilu_shift to support damping using the identity
- Added PCLUSetShift() or -pc_lu_shift to support damping using the identity
- Added PCICCSetShift() or -pc_icc_shift to support damping using the identity

KSP:

- Added a new ksp_type LGMRES
- Added KSPSetComputeSingularValues() support to ksp_type FGMRES

TS:

- Added support for Runge-Kutta using ts_type TS_RUNGE_KUTTA

DMMG:

- -dmmg_jacobian_period -1 => jacobian is frozen after initial construction

DA:

- Allow user preallocation of jacobian using DASetGetMatrix()
- DAGetMatrix now correctly returns the requested type.
- -mat_type typename overloads the requested type for DAGetMatrix

SYS:

- Added new viewer_type PETSC_VIEWER_NETCDF, PETSC_VIEWER_HDF4
- PETSc error handlers now trap many more signals.

Fortran:

- PetscPushErrorHandler() and PetscPopErrorHandler() now supported
- PetscPrintf() and PetscSynchronizedPrintf() now work in fortran with a single string

External Packages:

- Added TSPVodeGetParameters()
- Parmetis-3 support added using MatPartitionSetNParts(), ISPartitionCount()
- MUMPS support added, including complex (using mat_type MATAIJMUMPS, MATSBAIJMUMPS)
- Updated SuperLU_DIST interface to SuperLU_DIST_2.0
- Added Spooles complex support
- Added Spooles cholesky for SeqAIJ
- ADIC: ad_GRAD_MAX is now set in the application and compiled into code when compiling appplication
- The following variable names - in the buildsystem are changed - that correspond with SuperLU_DIST
  SUPERLUDIST_INCLUDE -> SUPERLU_DIST_INCLUDE
  SUPERLUDIST_LIB -> SUPERLU_DIST_LIB
  PETSCHAVE_SUPERLU -> PETSC_HAVE_SUPERLU