#include "petscis.h" PetscErrorCode ISListToPair(MPI_Comm comm, PetscInt listlen, IS islist, IS *xis, IS *yis)
Collective on comm.
|listlen||- IS list length|
|islist||- IS list|
|xis||- domain IS|
|yis||- range IS|
The ISs on the input list can belong to subcommunicators of comm, and the subcommunicators on the input IS list are assumed to be in a "deadlock-free" order.
Local lists of PetscObjects (or their subcommes) on a comm are "deadlock-free" if subcomm1 preceeds subcomm2 on any local list, then it preceeds subcomm2 on all ranks. Equivalently, the local numbers of the subcomms on each local list are drawn from some global numbering. This is ensured, for example, by ISPairToList().