MPI_Type_create_subarray(3OpenMPI)										MPI_Type_create_subarray(3OpenMPI)

NAME

       MPI_Type_create_subarray - Creates a data type describing an n-dimensional subarray of an n-dimensional array.

SYNTAX

C Syntax
       #include <mpi.h>
       int MPI_Type_create_subarray(int ndims, int array_of_sizes[], int array_of_subsizes[], int array_of_starts[], int order, MPI_Datatype oldtype, MPI_Datatype *newtype)

Fortran Syntax
       INCLUDE 'mpif.h'
       MPI_TYPE_CREATE_SUBARRAY(NDIMS, ARRAY_OF_SIZES, ARRAY_OF_SUBSIZES,
	    ARRAY_OF_STARTS, ORDER, OLDTYPE, NEWTYPE, IERROR)

	    INTEGER   NDIMS, ARRAY_OF_SIZES(*), ARRAY_OF_SUBSIZES(*),
	    ARRAY_OF_STARTS(*), ORDER, OLDTYPE, NEWTYPE, IERROR

C++ Syntax
       #include <mpi.h>
       MPI::Datatype MPI::Datatype::Create_subarray(int ndims,
	    const int array_of_sizes[], const int array_of_subsizes[],
	    const int array_of_starts[], int order) const

INPUT PARAMETERS

       ndims	 Number of array dimensions (positive integer).

       array_of_sizes
		 Number of elements of type oldtype in each dimension of the full array (array of positive integers).

       array_of_subsizes
		 Number of elements of type oldtype in each dimension of the subarray (array of positive integers).

       array_of_starts
		 Starting coordinates of the subarray in each dimension (array of nonnegative integers).

       order	 Array storage order flag (state).

       oldtype	 Array element data type (handle).

OUTPUT PARAMETERS

       newtype	 New data type (handle).

       IERROR	 Fortran only: Error status (integer).

DESCRIPTION

       The  subarray type constructor creates an MPI data type describing an n-dimensional subarray of an n-dimensional array. The subarray may be
       situated anywhere within the full array, and may be of any nonzero size up to the size of the larger array as long as it is confined within
       this  array.  This type constructor facilitates creating file types to access arrays distributed in blocks among processes to a single file
       that contains the global array.

       This type constructor can handle arrays with an arbitrary number of dimensions and works for both C- and Fortran-ordered matrices (that is,
       row-major or column-major). Note that a C program may use Fortran order and a Fortran program may use C order.

       The  ndims  parameter  specifies  the  number  of  dimensions  in  the  full data array and gives the number of elements in array_of_sizes,
       array_of_subsizes, and array_of_starts.

       The number of elements of type oldtype in each  dimension  of  the  n-dimensional  array  and  the  requested  subarray	are  specified	by
       array_of_sizes  and  array_of_subsizes,	respectively.  For  any  dimension  i,	it  is	erroneous  to  specify array_of_subsizes[i] < 1 or
       array_of_subsizes[i] > array of sizes[i].

       The array_of_starts contains the starting coordinates of each dimension of the subarray. Arrays are assumed to  be  indexed  starting  from
       zero. For any dimension i, it is erroneous to specify

       array_of_starts[i] < 0

       or

       array_of_starts[i] > (array_of_sizes[i] - array_of_subsizes[i]).

       The order argument specifies the storage order for the subarray as well as the full array. It must be set to one of the following:

       - MPI_ORDER_C: The ordering used by C arrays, (that is, row-major order)

       - MPI_ORDER_FORTRAN: The ordering used by Fortran arrays, (that is, column-major order)

       A ndims-dimensional subarray (newtype) with no extra padding can be defined by the function Subarray() as follows:

	  newtype = Subarray(ndims, {size , size ,..., size	  },
					 0	1	    ndims-1
		    {subsize , subsize , ..., subsize	    },
			    0	      1 	      ndims-1
		    {start , start , ..., start       }, oldtype)
			  0	  1		bduns-1

       Let the typemap of oldtype have the form:

	  {(type , disp ), (type , disp ), ..., (type	, disp	 )}
		0      0	1      1	      n-1      n-1

       where typei is a predefined MPI data type, and let ex be the extent of oldtype.

       The Subarray() function is defined recursively in three equations on page 72 of the MPI-2 standard.

       For an example use of MPI_Type_create_subarray in the context of I/O, see Section 9.9.2 of the MPI-2 standard.

NOTES

       In  a  Fortran program with arrays indexed starting from 1, if the starting coordinate of a particular dimension of the subarray is n, then
       the entry in array of starts for that dimension is n-1.

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++ func-
       tions  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.

       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.

Open MPI 1.2							  September 2006				MPI_Type_create_subarray(3OpenMPI)