.\"Copyright 2006-2008 Sun Microsystems, Inc.
.\"Copyright (c) 1996 Thinking Machines
.TH MPI_Topo_test 3 "Dec 08, 2009" "1.4" "Open MPI"
.SH NAME
\fBMPI_Topo_test\fP \- Determines the type of topology (if any) associated with a communicator.

.SH SYNTAX
.ft R
.SH C Syntax
.nf
#include <mpi.h>
int MPI_Topo_test(MPI_Comm \fIcomm\fP, int\fI *top_type\fP)

.SH Fortran Syntax
.nf
INCLUDE 'mpif.h'
MPI_TOPO_TEST(\fICOMM, TOP_TYPE, IERROR\fP)
	INTEGER	\fICOMM, TOP_TYPE, IERROR\fP

.SH C++ Syntax
.nf
#include <mpi.h>
int Comm::Get_topology() const

.SH INPUT PARAMETER
.ft R
.TP 1i
comm
Communicator (handle).

.SH OUTPUT PARAMETERS
.ft R
.TP 1i
top_type
Topology type of communicator comm (choice).
.ft R
.TP 1i
IERROR
Fortran only: Error status (integer). 

.SH DESCRIPTION
.ft R
The function MPI_Topo_test returns the type of topology that is assigned to a communicator.
.sp
The output value \fItop_type\fP is one of the following:
.sp
.nf
    MPI_GRAPH		graph topology
    MPI_CART		Cartesian topology
    MPI_UNDEFINED	no topology

.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.  

.SH SEE ALSO
MPI_Graph_create
.br
MPI_Cart_create