# PETSc

NEW FEATURES and CHANGES in PETSc 2.0.16

General:

- Added the option -compare option for incremental debugging; see the users manual for more details.
- Added tags file so that vi users can easily browse PETSc source files (just as emacs users already can by using etags). See the users manual subsection "VI users" for details.
- We have stopped distributing the UNIX-style manpages with PETSc. Instead, we now only distribute the HTML version. You can still access the man pages with the command $PETSC_DIR/bin/petscman. Alternatively, you can directly view $PETSC_DIR/docs/www/www.html.

TS (Timestepping Solvers):

SNES (Nonlinear Solvers):

- You can now attach several SNES monitoring routines with SNESMonitorSet() instead of only one as previously allowed. Similarly, multiple monitors can be used from the options database (e.g., -snes_monitor and -snes_xmonitor).

SLES (Linear Solvers):

- See PC and KSP

KSP (Krylov Subspace Methods):

- You can now attach several KSP monitoring routines with KSPSetMonitor() instead of only one as previously allowed. Similarly, multiple monitors can be used from the options database (e.g., -ksp_monitor and -ksp_xmonitor).

PC (Preconditioners):

MAT (Matrices):

- Added the routines MatSetValuesLocal(), MatZeroRowsLocal() and MatSetLocalToGlobalMapping() to enable the user to set values in a matrix using a local numbering of the nodes rather than a global numbering.
- Added the option MAT_IGNORE_OFF_PROC_ENTRIES for MatSetOptions(), which causes all entries on any processor destined to be stored on a different processor to be dropped instead. This is useful if you know that the "owning" processor is also always generating the correct entries, so PETSc need not ship over the duplicate entry generated on another processor. -
- Added options MAT_COLUMNS_UNSORTED and MAT_ROWS_UNSORTED for MatSetOptions() to enable switching betwen sorted and unsorted input.

DA (Distributed Arrays):

VEC (Vectors):

- Changed the SCATTER_ALL argument in VecScatterXXX() routines to SCATTER_FORWARD.
- Added the routines VecSetValuesLocal() and VecSetLocalToGlobalMapping() to allow the user to set values into a vector using a local numbering of the nodes rather than a global numbering.
- Added the routine VecSetOption(Vec,VEC_IGNORE_OFF_PROCESSOR_ENTRIES), which causes all entries on any processor destined to be stored on a different processor to be dropped instead. This is useful if you know that the "owning" processor is also always generating the correct entries, so PETSc need not transfer the duplicate entries generated on another processor.

IS (Index Sets):

Draw (Graphics):

- The numbers on the axis plots are much improved.
- You can now pass PETSC_DECIDE as the x and y arguments in DrawOpenX() and ViewerDrawOpenX() to let PETSc place non-overlapping windows on the display.

Viewers:

System Routines:

- Added routines PetscSynchronizedPrintf(MPI_Comm,format,args) and PetscSynchronizedFlush(MPI_Comm), which allow groups of processes to print to stdout as one would expect. I.e., the output from processor 0 is followed by the output from processor 1, etc. Very useful during code development. This can often be a substitute for attempting to sequentialize printf() statements via PetscSequentialPhaseBegin() and PetscSequentialPhaseEnd(). -
- Added the command line option -options_file <file> that causes all options in the specified file to be treated as if they were typed on the command line.
- Added the option -log_trace [filename] (and the corresponding routine PLogTraceBegin()) that allows tracing of all PETSc calls; useful to see where a program is hanging without running in the debugger. Can be used in conjunction with the -log_info option.
- Added PetscRandomSetInterval() to enable the user to set an interval over which random numbers will be uniformly distributed.

Event Logging:

Fortran Interface:

- Added the Fortran interface for VecDuplicateVecs(), VecDestroyVecs(), VecMAXPY(), VecMDot(), and VecMTDot().