MPI_Type_get_true_extent(3) Open MPI MPI_Type_get_true_extent(3)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.
SYNTAXC 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 parame‐
ter returns the true size of the data type, that is, the extent of the
corresponding typemap, ignoring MPI_LB and MPI_UB markers, and perform‐
ing 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++ 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.
1.7.4 Feb 04, 2014 MPI_Type_get_true_extent(3)
