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MPI_Type_vector - Creates a vector (strided) datatype.
#include <mpi.h>
int MPI_Type_vector(int count, int blocklength, int stride,
MPI_Datatype oldtype, MPI_Datatype *newtype)
INCLUDE ’mpif.h’
MPI_TYPE_VECTOR(COUNT, BLOCKLENGTH, STRIDE, OLDTYPE, NEWTYPE,
IERROR)
INTEGER COUNT, BLOCKLENGTH, STRIDE, OLDTYPE
INTEGER NEWTYPE, IERROR
#include <mpi.h>
Datatype Datatype::Create_vector(int count, int blocklength,
int stride) const
- 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).
- newtype
- New datatype (handle).
- IERROR
- Fortran only: Error
status (integer).
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.
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.
MPI_Type_create_hvector
MPI_Type_hvector
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