#include "petscis.h" PetscErrorCode ISIdentity(IS is,PetscBool *ident)Collective on IS
|is||- the index set|
|ident||- PETSC_TRUE if an identity, else PETSC_FALSE|
Note: If ISSetIdentity() (or ISSetInfo() for a permanent property) has been called, ISIdentity() will return its answer without communication between processes, but otherwise the output ident will be computed from ISGetInfo(), which may require synchronization on the communicator of IS. To avoid this computation, call ISGetInfo() directly with the compute flag set to PETSC_FALSE, and ident will be assumed false.