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)

       USE MPI
       ! or the older form: 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

Fortran 2008 Syntax

       USE mpi_f08
       MPI_Type_get_true_extent(datatype, true_lb, true_extent, ierror)
            TYPE(MPI_Datatype), INTENT(IN) :: datatype
            INTEGER(KIND=MPI_ADDRESS_KIND), INTENT(OUT) :: true_lb, true_extent
            INTEGER, OPTIONAL, INTENT(OUT) :: ierror
       MPI_Type_get_true_extent_x(datatype, true_lb, true_extent, ierror)
            TYPE(MPI_Datatype), INTENT(IN) :: datatype
            INTEGER(KIND = MPI_COUNT_KIND), INTENT(OUT) :: true_lb, true_extent
            INTEGER, OPTIONAL, INTENT(OUT) :: ierror

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.

4.1.6                                             Sep 30, 2023                       MPI_Type_get_true_extent(3)