Synopsis

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

Input Parameters

count

number of blocks — also number of entries in array_of_displacements and array_of_blocklengths (non-negative integer)

array_of_blocklengths

number of elements in each block (non-negative integer)

array_of_displacements

byte displacement of each block (integer)

oldtype

old datatype (handle)

Output Parameters

newtype

new datatype (handle)

Removed Function

The current MPI standard defines this routine as removed. The user should use the replacement routine. The replacement for this routine is 'MPI_Type_create_hindexed'.

Thread and Interrupt Safety

This routine is thread-safe. This means that this routine may be safely used by multiple threads without the need for any user-provided thread locks. However, the routine is not interrupt safe. Typically, this is due to the use of memory allocation routines such as 'malloc' or other non-MPICH runtime routines that are themselves not interrupt-safe.

Notes for Fortran

All MPI routines in Fortran (except for 'MPI_WTIME' and 'MPI_WTICK') have an additional argument 'ierr' at the end of the argument list. 'ierr' is an integer and has the same meaning as the return value of the routine in C. In Fortran, MPI routines are subroutines, and are invoked with the 'call' statement.

All MPI objects (e.g., 'MPI_Datatype', 'MPI_Comm') are of type 'INTEGER' in Fortran. The array_of_displacements are displacements, and are based on a zero origin. A common error is to do something like to following

integer a(100)
integer array_of_blocklengths(10), array_of_displacements(10)
do i=1,10
    array_of_blocklengths(i) = 1
    array_of_displacements(i) = (1 + (i-1)*10) * sizeofint
call MPI_TYPE_HINDEXED(10,array_of_blocklengths,array_of_displacements,MPI_INTEGER,newtype,ierr)
call MPI_TYPE_COMMIT(newtype,ierr)
call MPI_SEND(a,1,newtype,...)

expecting this to send "a(1),a(11),…​" because the array_of_displacements have values "1,11,…​". Because these are displacements from the beginning of "a", it actually sends "a(1+1),a(1+11),…​".

If you wish to consider the displacements as array_of_displacements into a Fortran array, consider declaring the Fortran array with a zero origin

integer a(0:99)

Errors

All MPI routines (except 'MPI_Wtime' and 'MPI_Wtick') return an error value; C routines as the value of the function and Fortran routines in the last argument. Before the value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job. The error handler may be changed with 'MPI_Comm_set_errhandler' (for communicators), 'MPI_File_set_errhandler' (for files), and 'MPI_Win_set_errhandler' (for RMA windows). The MPI-1 routine 'MPI_Errhandler_set' may be used but its use is deprecated. 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; however, MPI implementations will attempt to continue whenever possible.

  • MPI_SUCCESS - No error; MPI routine completed successfully.

  • MPI_ERR_OTHER - Other error; use 'MPI_Error_string' to get more information about this error code.