petsc-3.7.7 2017-09-25
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# PETSC_COMM_WORLD

the equivalent of the MPI_COMM_WORLD communicator which represents all the processs that PETSc knows about.

Notes: By default PETSC_COMM_WORLD and MPI_COMM_WORLD are identical unless you wish to run PETSc on ONLY a subset of MPI_COMM_WORLD. In that case create your new (smaller) communicator, call it, say comm, and set PETSC_COMM_WORLD = comm BEFORE calling PetscInitialize(), but after MPI_Init() has been called.

The value of PETSC_COMM_WORLD should never be USED/accessed before PetscInitialize() is called because it may not have a valid value yet.

### See Also

PETSC_COMM_SELF

Level:beginner
Location:include/petscsys.h
Index of all Sys routines
Table of Contents for all manual pages
Index of all manual pages

### Examples

src/sys/classes/viewer/examples/tutorials/ex1.c.html
src/sys/classes/viewer/examples/tutorials/ex2.c.html
src/sys/classes/viewer/examples/tutorials/ex1f90.F90.html
src/sys/classes/random/examples/tutorials/ex1.c.html
src/sys/classes/random/examples/tutorials/ex2.c.html
src/sys/examples/tutorials/ex1.c.html
src/sys/examples/tutorials/ex2.c.html
src/sys/examples/tutorials/ex4.c.html
src/sys/examples/tutorials/ex5.c.html
src/sys/examples/tutorials/ex9.c.html
src/sys/examples/tutorials/ex11.c.html