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MPI_Type_create_hindexed(3) man page (version 5.0.0rc2)

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Name

MPI_Type_indexed, MPI_Type_create_hindexed - Creates an indexed datatype.

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


USE MPI
! or the older form: 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

Fortran 2008 Syntax


USE mpi_f08
MPI_Type_indexed(count, array_of_blocklengths, array_of_displacements,
        oldtype, newtype, ierror)
    INTEGER, INTENT(IN) :: count, array_of_blocklengths(count),
    array_of_displacements(count)
    TYPE(MPI_Datatype), INTENT(IN) :: oldtype
    TYPE(MPI_Datatype), INTENT(OUT) :: newtype
    INTEGER, OPTIONAL, INTENT(OUT) :: ierror
MPI_Type_create_hindexed(count, array_of_blocklengths,
        array_of_displacements, oldtype, newtype, ierror)
    INTEGER, INTENT(IN) :: count, array_of_blocklengths(count)
    INTEGER(KIND=MPI_ADDRESS_KIND), INTENT(IN) ::
    array_of_displacements(count)
    TYPE(MPI_Datatype), INTENT(IN) :: oldtype
    TYPE(MPI_Datatype), INTENT(OUT) :: newtype
    INTEGER, OPTIONAL, INTENT(OUT) :: ierror

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.

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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