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MPI_Type_contiguous(3) man page (version 1.8.4)

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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

Input Parameters

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.


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