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MPI_Type_indexed(3) man page (version 1.2.9)

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NAME

       MPI_Type_indexed - Creates an indexed datatype.

SYNTAX


C Syntax

       #include <mpi.h>
       int MPI_Type_indexed(int count, int *array_of_blocklengths,
            int *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

C++ Syntax

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

INPUT PARAMETERS

       count     Number  of  blocks -- also number of entries in array_of_dis-
                 placements 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
                 (array of integer).

       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 multi-
       ples 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
       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,  new-
       type) where

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

       and

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

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++  func-
       tions  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_create_hindexed
       MPI_Type_hindexed

Open MPI 1.2                    September 2006      MPI_Type_indexed(3OpenMPI)

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