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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.
#include <mpi.h>
int MPI_Type_get_true_extent(MPI_Datatype datatype,
MPI_Aint *true_lb, MPI_Aint *true_extent)
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
#include <mpi.h>
void MPI::Datatype::Get_true_extent(MPI::Aint& true_lb,
MPI::Aint& true_extent) const
- datatype
- Data type for which information is wanted
(handle).
- true_lb
- True lower bound of data type (integer).
- true_extent
- True size of data type (integer).
- IERROR
- Fortran only: Error
status (integer).
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.
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.
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.
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