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MPI_Type_contiguous.3.rst

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MPI_Type_contiguous

:ref:`MPI_Type_contiguous` |mdash| Creates a contiguous datatype.

SYNTAX

C Syntax

#include <mpi.h>

int MPI_Type_contiguous(int count, MPI_Datatype oldtype,
     MPI_Datatype *newtype)

Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_TYPE_CONTIGUOUS(COUNT, OLDTYPE, NEWTYPE, IERROR)
     INTEGER COUNT, OLDTYPE, NEWTYPE, IERROR

Fortran 2008 Syntax

USE mpi_f08
MPI_Type_contiguous(count, oldtype, newtype, ierror)
     INTEGER, INTENT(IN) :: count
     TYPE(MPI_Datatype), INTENT(IN) :: oldtype
     TYPE(MPI_Datatype), INTENT(OUT) :: newtype
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

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 :ref:`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 the Datatypes chapter in the MPI Standard.

ERRORS