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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, old-
type, 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)}
(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++ 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.
SEE ALSO
MPI_Type_create_hvector
MPI_Type_hvector
1.3.4 Nov 11, 2009 MPI_Type_vector(3)
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