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Man Pages


Manual Reference Pages  -  MPI_TYPE_CREATE_HINDEXED (3)

NAME

MPI_Type_indexed, MPI_Type_create_hindexed - Creates an indexed datatype.

CONTENTS

Syntax
C Syntax
Fortran Syntax
C++ Syntax
Input Parameters
Output Parameters
Description
Errors
See Also

SYNTAX

C Syntax

#include <mpi.h>
int MPI_Type_indexed(int count, const int array_of_blocklengths[],
        const int array_of_displacements[], MPI_Datatype oldtype,
        MPI_Datatype *newtype)

int MPI_Type_create_hindexed(int count,         const int array_of_blocklengths[],         const MPI_Aint array_of_displacements[], MPI_Datatype oldtype,         MPI_Datatype *newtype)

Fortran Syntax

INCLUDE ’mpif.h’
MPI_TYPE_INDEXED(COUNT, ARRAY_OF_BLOCKLENGTHS,
                ARRAY_OF_DISPLACEMENTS, OLDTYPE, NEWTYPE, IERROR)
        INTEGER COUNT, ARRAY_OF_BLOCKLENGTHS(*)
        INTEGER ARRAY_OF_DISPLACEMENTS(*), OLDTYPE, NEWTYPE
        INTEGER IERROR

MPI_TYPE_CREATE_HINDEXED(COUNT, ARRAY_OF_BLOCKLENGTHS,                 ARRAY_OF_DISPLACEMENTS, OLDTYPE, NEWTYPE, IERROR)         INTEGER COUNT, ARRAY_OF_BLOCKLENGTHS(*)         INTEGER OLDTYPE, NEWTYPE         INTEGER(KIND=MPI_ADDRESS_KIND) ARRAY_OF_DISPLACEMENTS(*)         INTEGER IERROR

C++ Syntax

#include <mpi.h>
Datatype Datatype::Create_indexed(int count,
        const int array_of_blocklengths[],
        const int array_of_displacements[]) const

Datatype Datatype::Create_hindexed(int count,         const int array_of_blocklengths[],         const MPI::Aint array_of_displacements[]) const

INPUT PARAMETERS

count Number of blocks -- also number of entries in array_of_displacements and array_of_blocklengths (nonnegative integer).
array_of_blocklengths
  Number of elements per block (array of nonnegative integers).
array_of_displacements
  Displacement for each block, in multiples of oldtype extent for MPI_Type_indexed and bytes for MPI_Type_create_hindexed (array of integer for MPI_TYPE_INDEXED, array of MPI_Aint for MPI_TYPE_CREATE_HINDEXED).
oldtype Old datatype (handle).

OUTPUT PARAMETERS

newtype New datatype (handle).
IERROR Fortran only: Error status (integer).

DESCRIPTION

The function MPI_Type_indexed allows replication of an old datatype into a sequence of blocks (each block is a concatenation of the old datatype), where each block can contain a different number of copies and have a different displacement. All block displacements are multiples of the old data type’s extent.

Example: Let oldtype have type map {(double, 0), (char, 8)}, with extent 16. Let B = (3, 1) and let D = (4, 0). A call to MPI_Type_indexed(2, B, D, oldtype, newtype) returns a datatype with type map

    {(double, 64), (char, 72), (double, 80), (char, 88),
    (double, 96), (char, 104),
    (double, 0), (char, 8)}

That is, three copies of the old type starting at displacement 4 x 16 = 64, and one copy starting at displacement 0.

In general, assume that oldtype has type map

    {(type(0), disp(0)), ..., (type(n-1), disp(n-1))},

with extent ex. Let B be the array_of_blocklength argument and D be the array_of_displacements argument. The newly created datatype has


n x S ^count-1 i = 0 B[i] entries:

{(type(0), disp(0) + D[0]* ex), ..., (type(n-1), disp(n-1) + D[0]* ex), ..., (type(0), disp(0) + (D[0] + B[0]-1)* ex), ..., (type(n-1), disp(n-1) + (D[0]+ B[0]-1)* ex), ..., (type(0), disp(0) + D[count-1]* ex), ..., (type(n-1), disp(n-1) + D[count-1]* ex), ..., (type(0), disp(0) + (D[count-1] + B[count-1] -1)* ex), ..., (type(n-1), disp(n-1) + (D[count-1] + B[count-1] -1)* ex)}

A call to MPI_Type_vector(count, blocklength, stride, oldtype, newtype) is equivalent to a call to MPI_Type_indexed(count, B, D, oldtype, newtype) where

    D[j] = j * stride, j = 0,..., count-1   

and

B[j] = blocklength, j = 0, .., count-1

The function MPI_Type_create_hindexed is identical to MPI_Type_indexed, except that block displacements in array_of_displacements are specified in bytes, rather than in multiples of the oldtype extent.

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.

SEE ALSO

MPI_Type_hindexed

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1.10.2 MPI_TYPE_INDEXED (3) Jan 21, 2016

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