NAME

       MPI_Type_get_true_extent,  MPI_Type_get_true_extent_x - Returns the true lower bound and extent of a data
       type's corresponding typemap, ignoring MPI_UB and MPI_LB markers.

SYNTAX

C Syntax

       #include <mpi.h>
       int MPI_Type_get_true_extent(MPI_Datatype datatype,
            MPI_Aint *true_lb, MPI_Aint *true_extent)
       int MPI_Type_get_true_extent_x(MPI_Datatype datatype,
            MPI_Count *true_lb, MPI_Count *true_extent)

Fortran Syntax (see FORTRAN 77 NOTES)

       INCLUDE 'mpif.h'
       MPI_TYPE_GET_TRUE_EXTENT(DATATYPE, TRUE_LB, TRUE_EXTENT, IERROR)
            INTEGER   DATATYPE, IERROR
            INTEGER(KIND=MPI_ADDRESS_KIND) TRUE_LB, TRUE_EXTENT
       MPI_TYPE_GET_TRUE_EXTENT_X(DATATYPE, TRUE_LB, TRUE_EXTENT, IERROR)
            INTEGER   DATATYPE, IERROR
            INTEGER(KIND=MPI_COUNT_KIND) TRUE_LB, TRUE_EXTENT

C++ Syntax

       #include <mpi.h>
       void MPI::Datatype::Get_true_extent(MPI::Aint& true_lb,
            MPI::Aint& true_extent) const

INPUT PARAMETER

       datatype  Data type for which information is wanted (handle).

OUTPUT PARAMETERS

       true_lb   True lower bound of data type (integer).

       true_extent
                 True size of data type (integer).

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       The true_lb parameter returns the offset of the lowest unit of store that is addressed by the data  type,
       that is, the lower bound of the corresponding typemap, ignoring MPI_LB markers. The true_extent parameter
       returns the true size of the data type, that is, the extent of the corresponding typemap, ignoring MPI_LB
       and  MPI_UB  markers, and performing no rounding for alignment. For both functions, if either the true_lb
       or true_extent parameter cannot express the value to be returned (e.g., if the parameter is too small  to
       hold the output value), it is set to MPI_UNDEFINED.

       The true_extent is the minimum number of bytes of memory necessary to hold a data type, uncompressed.

       See  §  4.1.8  of the MPI-3 standard for more detailed definitions of these parameters in relation to the
       typemap.

FORTRAN 77 NOTES

       The MPI standard prescribes portable Fortran syntax for the TRUE_LB and TRUE_EXTENT  arguments  only  for
       Fortran 90. FORTRAN 77 users may use the non-portable syntax

       MPI_Type_get_true_extent:

            INTEGER*MPI_ADDRESS_KIND TRUE_LB
       or
            INTEGER*MPI_ADDRESS_KIND TRUE_EXTENT

       MPI_Type_get_true_extent_x:

            INTEGER*MPI_COUNT_KIND TRUE_LB
       or
            INTEGER*MPI_COUNT_KIND TRUE_EXTENT

       where  MPI_ADDRESS_KIND  and  MPI_COUNT_KIND  are  constants defined in mpif.h and give the length of the
       declared integer in bytes.

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.