/*D
   MPI_Group_rank - Returns the rank of this process in the given group

Synopsis:
.vb
int MPI_Group_rank(MPI_Group group, int *rank)
.ve

Input Parameters:
. group - group (handle)

Output Parameters:
. rank - rank of the calling process in group, or MPI_UNDEFINED if the process is not a member (integer)

.N ThreadSafe

.N Fortran

.N Errors
.N MPI_SUCCESS
.N MPI_ERR_ARG
.N MPI_ERR_GROUP
.N MPI_ERR_OTHER

D*/

