.\" -*- nroff -*-
.\" Copyright 2010 Cisco Systems, Inc.  All rights reserved.
.\" Copyright 2006-2008 Sun Microsystems, Inc.
.\" Copyright (c) 1996 Thinking Machines Corporation
.\" $COPYRIGHT$
.TH MPI_Group_compare 3 "May 26, 2022" "4.1.4" "Open MPI"
.SH NAME
\fBMPI_Group_compare \fP \- Compares two groups.

.SH SYNTAX
.SH C Syntax
.nf
#include <mpi.h>
int MPI_Group_compare(MPI_Group \fIgroup1\fP, MPI_Group\fI group2\fP,
	int\fI *result\fP)

.fi
.SH Fortran Syntax
.nf
USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_GROUP_COMPARE(\fIGROUP1, GROUP2, RESULT, IERROR\fP)
	INTEGER	\fIGROUP1, GROUP2, RESULT, IERROR\fP

.fi
.SH Fortran 2008 Syntax
.nf
USE mpi_f08
MPI_Group_compare(\fIgroup1\fP, \fIgroup2\fP, \fIresult\fP, \fIierror\fP)
	TYPE(MPI_Group), INTENT(IN) :: \fIgroup1\fP, \fIgroup2\fP
	INTEGER, INTENT(OUT) :: \fIresult\fP
	INTEGER, OPTIONAL, INTENT(OUT) :: \fIierror\fP

.fi
.SH C++ Syntax
.nf
#include <mpi.h>
static int Group::Compare(const Group& \fIgroup1\fP, const Group& \fIgroup2\fP)

.fi
.SH INPUT PARAMETERS
.ft R
.TP 1i
group1
First group (handle).
.TP 1i
group2
Second group (handle).

.SH OUTPUT PARAMETERS
.ft R
.TP 1i
result
Integer which is MPI_IDENT if the order and members of the two groups are the same, MPI_SIMILAR if only the members are the same, and MPI_UNEQUAL otherwise.
.ft R
.TP 1i
IERROR
Fortran only: Error status (integer).

.SH DESCRIPTION
.ft R
MPI_IDENT results if the group members and group order is exactly the same in both groups. This happens for instance if group1 and group2 are the same handle. MPI_SIMILAR results if the group members are the same but the order is different. MPI_UNEQUAL results otherwise.

.SH ERRORS
Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument. C++ functions do not return errors. If the default error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism will be used to throw an MPI::Exception object.
.sp
Before the error value is returned, the current MPI error handler is
called. By default, this error handler aborts the MPI job, except for I/O function errors. The error handler may be changed with MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.