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MPI_Type_commit(3) man page (version 1.8)

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Name

MPI_Type_commit - Commits a data type.

Syntax

C Syntax


#include <mpi.h>
int MPI_Type_commit(MPI_Datatype *datatype)

Fortran Syntax


INCLUDE ’mpif.h’
MPI_TYPE_COMMIT(DATATYPE, IERROR)
    INTEGER    DATATYPE, IERROR

C++ Syntax


#include <mpi.h>
void Datatype::Commit()

Input Parameter

datatype
Data type (handle).

Output Parameter

IERROR
Fortran only: Error status (integer).

Description

The commit operation commits the data type. A data type is the formal description of a communication buffer, not the content of that buffer. After a data type has been committed, it can be repeatedly reused to communicate the changing content of a buffer or, indeed, the content of different buffers, with different starting addresses.

Example: The following Fortran code fragment gives examples of using MPI_Type_commit.


    INTEGER type1, type2
    CALL MPI_TYPE_CONTIGUOUS(5, MPI_REAL, type1, ierr)
                  ! new type object created
    CALL MPI_TYPE_COMMIT(type1, ierr)
                  ! now type1 can be used for communication

If the data type specified in datatype is already committed, it is equivalent to a no-op.

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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