Provided by: openmpi-doc_1.6.5-8_all
NAME
MPI_Type_get_true_extent - 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)
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
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. The true_extent is the minimum number of bytes of memory necessary to hold a data type, uncompressed. See Section 4.14.3 of the MPI-2 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 INTEGER*MPI_ADDRESS_KIND TRUE_LB or INTEGER*MPI_ADDRESS_KIND TRUE_EXTENT where MPI_ADDRESS_KIND is a constant defined in mpif.h and gives 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.