ISAllGather

Given an index set (IS) on each processor, generates a large index set (same on each processor) by concatenating together each processors index set.

Synopsis

#include "petscsys.h" 
#include "petscis.h"  
int ISAllGather(IS is,IS *isout)

Collective on IS

Input Parameter

is -the distributed index set

Output Parameter

isout -the concatenated index set (same on all processors)

Notes

ISAllGather() is clearly not scalable for large index sets.

The IS created on each processor must be created with a common communicator (e.g., PETSC_COMM_WORLD). If the index sets were created with PETSC_COMM_SELF, this routine will not work as expected, since each process will generate its own new IS that consists only of itself.

Examples