Creates a data structure for an index set containing a list of integers. The indices are relative to entries, not blocks.


#include "petscis.h"     
PetscErrorCode  ISCreateBlock(MPI_Comm comm,PetscInt bs,PetscInt n,const PetscInt idx[],PetscCopyMode mode,IS *is)

Input Parameters

comm - the MPI communicator
bs - number of elements in each block
n - the length of the index set (the number of blocks)
idx - the list of integers, one for each block and count of block not indices
mode - see PetscCopyMode, only PETSC_COPY_VALUES and PETSC_OWN_POINTER are supported in this routine

Output Parameter

is - the new index set


When the communicator is not MPI_COMM_SELF, the operations on the index sets, IS, are NOT conceptually the same as MPI_Group operations. The index sets are then distributed sets of indices and thus certain operations on them are collective.


If you wish to index the values {0,1,6,7}, then use a block size of 2 and idx of {0,3}.

Level: beginner

See Also

ISCreateStride(), ISCreateGeneral(), ISAllGather()