# MPI_Cart_map

Maps process to Cartesian topology information

## Synopsis

    #include "mpi.h"
    int MPI_Cart_map (
     MPI_Comm comm_old,
     int ndims,
     int *dims,
     int *periods,
     int *newrank)

## Input Parameters

| comm | input communicator (handle)
| ndims | number of dimensions of cartesian structure (integer)
| dims | integer array of size `ndims` specifying the number of processes in each coordinate direction
| periods | logical array of size `ndims` specifying the periodicity specification in each coordinate direction

## Output Parameter

newrank
  reordered rank of the calling process; `MPI_UNDEFINED` if calling process does not belong to grid (integer)

## Notes for Fortran

All MPI routines in Fortran (except for `MPI_WTIME` and `MPI_WTICK`) have an additional argument `ierr` at the end of the argument list. `ierr` is an integer and has the same meaning as the return value of the routine in C. In Fortran, MPI routines are subroutines, and are invoked with the `call` statement.

All MPI objects (e.g., `MPI_Datatype`, `MPI_Comm`) are of type `INTEGER` in Fortran.

## Errors

All MPI routines (except `MPI_Wtime` and `MPI_Wtick`) return an error value; C routines as the value of the function and Fortran routines in the last argument. Before the value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job. The error handler may be changed with `MPI_Errhandler_set`; the predefined error handler `MPI_ERRORS_RETURN` may be used to cause error values to be returned. Note that MPI does not guarentee that an MPI program can continue past an error.

MPI_SUCCESS
  No error; MPI routine completed successfully.

MPI_ERR_COMM
  Invalid communicator. A common error is to use a null communicator in a call (not even allowed in `MPI_Comm_rank`).

MPI_ERR_DIMS
  Illegal dimension argument. A dimension argument is null or its length is less than or equal to zero.

MPI_ERR_ARG
  Invalid argument. Some argument is invalid and is not identified by a specific error class (e.g., `MPI_ERR_RANK`).

Location:cart_map.c