MPI_Type_create_subarray(3)        Open MPI        MPI_Type_create_subarray(3)



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++
       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.

       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.





1.4.1                            Jan 14, 2010      MPI_Type_create_subarray(3)
