NAME¶
MPI_Type_contiguous - Creates a contiguous datatype.
SYNTAX¶
C Syntax¶
#include <mpi.h>
int MPI_Type_contiguous(int count, MPI_Datatype oldtype,
MPI_Datatype *newtype)
Fortran Syntax¶
INCLUDE 'mpif.h'
MPI_TYPE_CONTIGUOUS( COUNT, OLDTYPE, NEWTYPE, IERROR)
INTEGER COUNT, OLDTYPE, NEWTYPE, IERROR
C++ Syntax¶
#include <mpi.h>
Datatype Datatype::Create_contiguous(int count) const
- count
- Replication count (nonnegative integer).
- oldtype
- Old datatype (handle).
OUTPUT PARAMETERS¶
- newtype
- New datatype (handle).
- IERROR
- Fortran only: Error status (integer).
DESCRIPTION¶
The simplest datatype constructor is MPI_Type_contiguous, which allows
replication of a datatype into contiguous locations.
newtype is the datatype obtained by concatenating
count copies of
oldtype. Concatenation is defined using the extent of
oldtype as
the size of the concatenated copies.
Example: Let oldtype have type map {(double, 0), (char, 8)}, with extent
16, and let count = 3. The type map of the datatype returned by newtype is
{(double, 0), (char, 8), (double, 16), (char, 24),
(double, 32), (char, 40)];
i.e., alternating double and char elements, with displacements 0, 8, 16, 24, 32,
40.
In general, assume that the type map of oldtype is
{(type(0), disp(0)),...,(type(n-1), disp(n-1))},
with extent ex. Then newtype has a type map with count times n entries defined
by:
{(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) + ex * (count - 1)),
...,(type(n-1), disp(n-1) + ex * (count - 1))}.
For more information about derived datatypes, see Section 3.12 of the MPI-1
Standard.
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.