MPI_Type_vector(3)                 Open MPI                 MPI_Type_vector(3)



NAME
       MPI_Type_vector - Creates a vector (strided) datatype.


SYNTAX
C Syntax
       #include <mpi.h>
       int MPI_Type_vector(int count, int blocklength, int stride,
            MPI_Datatype oldtype, MPI_Datatype *newtype)


Fortran Syntax
       INCLUDE 'mpif.h'
       MPI_TYPE_VECTOR(COUNT, BLOCKLENGTH, STRIDE, OLDTYPE, NEWTYPE,
                 IERROR)
            INTEGER   COUNT, BLOCKLENGTH, STRIDE, OLDTYPE
            INTEGER   NEWTYPE, IERROR


C++ Syntax
       #include <mpi.h>
       Datatype Datatype::Create_vector(int count, int blocklength,
            int stride) const


INPUT PARAMETERS
       count     Number of blocks (nonnegative integer).

       blocklength
                 Number of elements in each block (nonnegative integer).

       stride    Number of elements between start of each block (integer).

       oldtype   Old datatype (handle).



OUTPUT PARAMETERS
       newtype   New datatype (handle).


       IERROR    Fortran only: Error status (integer).


DESCRIPTION
       The function MPI_Type_vector is a general constructor that allows
       replication of a datatype into locations that consist of equally spaced
       blocks. Each block is obtained by concatenating the same number of
       copies of the old datatype. The spacing between blocks is a multiple of
       the extent of the old datatype.

       Example 1: Assume, again, that oldtype has type map {(double, 0),
       (char, 8)}, with extent 16. A call to  MPI_Type_vector(2, 3, 4,
       oldtype, newtype) will create the datatype with type map
           {(double, 0), (char, 8), (double, 16), (char, 24),
           (double, 32), (char, 40),
           (double, 64), (char, 72),
           (double, 80), (char, 88), (double, 96), (char, 104)}

       That is, two blocks with three copies each of the old type, with a
       stride of 4 elements (4 x 6 bytes) between the blocks.

       Example 2:  A call to  MPI_Type_vector(3, 1, -2, oldtype, newtype) will
       create the datatype

           {(double, 0), (char, 8), (double, -32), (char, -24),
           (double, -64), (char, -56)}

       In general, assume that oldtype has type map

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

       with extent ex. Let bl be the blocklength. The newly created datatype
       has a type map with count x bl x  n entries:

           {(type(0), disp(0)), ..., (type(n-1), disp(n-1)),
           (type(0), disp(0) + ex), ..., (type(n-1), disp(n-1) + ex), ...,
           (type(0), disp(0) + (bl -1) * ex),...,
           (type(n-1), disp(n-1) + (bl -1)* ex),
           (type(0), disp(0) + stride * ex),..., (type(n-1),
           disp(n-1) + stride * ex), ...,
           (type(0), disp(0) + (stride + bl - 1) * ex), ...,
           (type(n-1), disp(n-1) + (stride + bl -1) * ex), ...,
           (type(0), disp(0) + stride * (count -1) * ex), ...,
           (type(n-1), disp(n-1) + stride * (count -1) * ex), ...,
           (type(0), disp(0) + (stride * (count -1) + bl -1) * ex), ...,
           (type(n-1), disp(n-1) + (stride * (count -1) + bl -1) * ex)}

       A call to MPI_Type_contiguous(count, oldtype, newtype) is equivalent to
       a call to MPI_Type_vector(count, 1, 1, oldtype, newtype), or to a call
       to MPI_Type_vector(1, count, n, oldtype, newtype), n arbitrary.


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.


SEE ALSO
       MPI_Type_create_hvector
       MPI_Type_hvector




1.4.1                            Jan 14, 2010               MPI_Type_vector(3)
