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) |
USE MPI
! or the older form: INCLUDE ’mpif.h’
MPI_TYPE_VECTOR(COUNT, BLOCKLENGTH, STRIDE, OLDTYPE,
NEWTYPE,
IERROR) |
||||
INTEGER |
COUNT, BLOCKLENGTH, STRIDE, OLDTYPE | |||
INTEGER |
NEWTYPE, IERROR |
USE mpi_f08
MPI_Type_vector(count, blocklength,
stride, oldtype, newtype,
ierror)
INTEGER, INTENT(IN) :: count, blocklength, stride | |
TYPE(MPI_Datatype), INTENT(IN) :: oldtype | |
TYPE(MPI_Datatype), INTENT(OUT) :: newtype | |
INTEGER, OPTIONAL, INTENT(OUT) :: ierror |
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