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.TH "MPI_CART_MAP" "3" "Jul 22, 2024" "" "Open MPI"
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\fI\%MPI_Cart_map\fP — Maps process to Cartesian topology information.
.SH SYNTAX
.SS C Syntax
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.INDENT 3.5
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.nf
.ft C
#include <mpi.h>

int MPI_Cart_map(MPI_Comm comm, int ndims, const int dims[],
    const int periods[], int *newrank)
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.SS Fortran Syntax
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.nf
.ft C
USE MPI
! or the older form: INCLUDE \(aqmpif.h\(aq

MPI_CART_MAP(COMM, NDIMS, DIMS, PERIODS, NEWRANK, IERROR)
    INTEGER COMM, NDIMS, DIMS(*), NEWRANK, IERROR
    LOGICAL PERIODS(*)
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.SS Fortran 2008 Syntax
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.ft C
USE mpi_f08

MPI_Cart_map(comm, ndims, dims, periods, newrank, ierror)
    TYPE(MPI_Comm), INTENT(IN) :: comm
    INTEGER, INTENT(IN) :: ndims, dims(ndims)
    LOGICAL, INTENT(IN) :: periods(ndims)
    INTEGER, INTENT(OUT) :: newrank
    INTEGER, OPTIONAL, INTENT(OUT) :: ierror
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.SH INPUT PARAMETERS
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.IP \(bu 2
\fBcomm\fP : Input communicator (handle).
.IP \(bu 2
\fBndims\fP : Number of dimensions of Cartesian structure (integer).
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.B \fBdims\fP
Integer array of size ndims specifying the number of processes
in each coordinate direction.
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.IP \(bu 2
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.B \fBperiods\fP
Logical array of size ndims specifying the periodicity
specification in each coordinate direction.
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.SH OUTPUT PARAMETERS
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.IP \(bu 2
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.B \fBnewrank\fP
Reordered rank of the calling process; MPI_UNDEFINED if
calling process does not belong to grid (integer).
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.IP \(bu 2
\fBierror\fP : Fortran only: Error status (integer).
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.SH DESCRIPTION
.sp
\fI\%MPI_Cart_map\fP and \fI\%MPI_Graph_map\fP can be used to implement all other
topology functions. In general they will not be called by the user
directly, unless he or she is creating additional virtual topology
capability other than that provided by MPI. \fI\%MPI_Cart_map\fP computes an
“optimal” placement for the calling process on the physical machine. A
possible implementation of this function is to always return the rank of
the calling process, that is, not to perform any reordering.
.SH ERRORS
.sp
Almost all MPI routines return an error value; C routines as the return result
of the function and Fortran routines in the last argument.
.sp
Before the error value is returned, the current MPI error handler associated
with the communication object (e.g., communicator, window, file) is called.
If no communication object is associated with the MPI call, then the call is
considered attached to MPI_COMM_SELF and will call the associated MPI error
handler. When MPI_COMM_SELF is not initialized (i.e., before
\fI\%MPI_Init\fP/\fI\%MPI_Init_thread\fP, after \fI\%MPI_Finalize\fP, or when using the Sessions
Model exclusively) the error raises the initial error handler. The initial
error handler can be changed by calling \fI\%MPI_Comm_set_errhandler\fP on
MPI_COMM_SELF when using the World model, or the mpi_initial_errhandler CLI
argument to mpiexec or info key to \fI\%MPI_Comm_spawn\fP/\fI\%MPI_Comm_spawn_multiple\fP\&.
If no other appropriate error handler has been set, then the MPI_ERRORS_RETURN
error handler is called for MPI I/O functions and the MPI_ERRORS_ABORT error
handler is called for all other MPI functions.
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Open MPI includes three predefined error handlers that can be used:
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\fBMPI_ERRORS_ARE_FATAL\fP
Causes the program to abort all connected MPI processes.
.IP \(bu 2
\fBMPI_ERRORS_ABORT\fP
An error handler that can be invoked on a communicator,
window, file, or session. When called on a communicator, it
acts as if \fI\%MPI_Abort\fP was called on that communicator. If
called on a window or file, acts as if \fI\%MPI_Abort\fP was called
on a communicator containing the group of processes in the
corresponding window or file. If called on a session,
aborts only the local process.
.IP \(bu 2
\fBMPI_ERRORS_RETURN\fP
Returns an error code to the application.
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MPI applications can also implement their own error handlers by calling:
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.IP \(bu 2
\fI\%MPI_Comm_create_errhandler\fP then \fI\%MPI_Comm_set_errhandler\fP
.IP \(bu 2
\fI\%MPI_File_create_errhandler\fP then \fI\%MPI_File_set_errhandler\fP
.IP \(bu 2
\fI\%MPI_Session_create_errhandler\fP then \fI\%MPI_Session_set_errhandler\fP or at \fI\%MPI_Session_init\fP
.IP \(bu 2
\fI\%MPI_Win_create_errhandler\fP then \fI\%MPI_Win_set_errhandler\fP
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Note that MPI does not guarantee that an MPI program can continue past
an error.
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See the \fI\%MPI man page\fP for a full list of \fI\%MPI error codes\fP\&.
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See the Error Handling section of the MPI\-3.1 standard for
more information.
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\fBSEE ALSO:\fP
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.IP \(bu 2
\fI\%MPI_Graph_map\fP
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.SH COPYRIGHT
2003-2024, The Open MPI Community
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