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MPI_Type_match_size.3.rst

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MPI_Type_match_size

:ref:`MPI_Type_match_size` |mdash| Returns an MPI datatype of a given type and size

SYNTAX

C Syntax

#include <mpi.h>

int MPI_Type_match_size(int typeclass, int size,
     MPI_Datatype *type)

Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_TYPE_MATCH_SIZE(TYPECLASS, SIZE, TYPE, IERROR)
     INTEGER TYPECLASS, SIZE, TYPE, IERROR

Fortran 2008 Syntax

USE mpi_f08
MPI_Type_match_size(typeclass, size, datatype, ierror)
     INTEGER, INTENT(IN) :: typeclass, size
     TYPE(MPI_Datatype), INTENT(OUT) :: datatype
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT PARAMETERS

  • typeclass: Generic type specifier (integer).
  • size: Size, in bytes, of representation (integer).

OUTPUT PARAMETERS

  • type: Datatype with correct type and size (handle).
  • ierror: Fortran only: Error status (integer).

DESCRIPTION

The function returns an MPI datatype matching a local variable of type (typeclass, size). The returned type is a reference (handle) to a predefined named datatype, not a duplicate. This type cannot be freed.

The value of typeclass may be set to one of MPI_TYPECLASS_REAL, MPI_TYPECLASS_INTEGER, or MPI_TYPECLASS_COMPLEX, corresponding to the desired datatype.

MPI_type_match_size can be used to obtain a size-specific type that matches a Fortran numeric intrinsic type: first call :ref:`MPI_Sizeof` to compute the variable size, then call :ref:`MPI_Type_match_size` to find a suitable datatype. In C use the sizeof builtin instead of :ref:`MPI_Sizeof`.

It is erroneous to specify a size not supported by the compiler.

ERRORS

.. seealso::
   * :ref:`MPI_Sizeof`
   * :ref:`MPI_Type_get_extent`