NAME

MPI_Type_extent - Returns the extent of a type in bytes

SYNOPSIS

#include <mpi.h> 
int MPI_Type_extent(MPI_Datatype datatype , MPI_Aint *extent ); 
#include <pmpi.h> 
int PMPI_Type_extent(MPI_Datatype datatype , MPI_Aint *extent ); 
INCLUDE 'mpif.h' 
MPI_TYPE_EXTENT(datatype , extent , ierr ) 
INTEGER  datatype ,  extent ,  ierr 

INPUT PARAMETER

datatype - type (handle)

OUTPUT PARAMETER

extent - extent of the type (integer).

DESCRIPTION

The MPI_Type_extent() function is used to determine the extent of a type datatype . The extent is defined to be the difference in offsets from the upper and lower bounds of a type. Note that it is possible to alter the upper and lower bounds through the use of the MPI_UB and MPI_LB types in constructing a user defined type. Thus this "effective" extent may not correspond to the actual extent of memory accessed by users of this type. Use the MPI_Type_get_true_extent() function to access that information if required.

Note that the FORTRAN version of this function only returns a 32-bit value. Use .B MPI_Type_get_true_extent() to get the full 64-bits.

PMPI_Type_extent() is the profiling version of this function.

ERRORS

All MPI routines except for MPI_Wtime and MPI_Wtick return an error code. The the current MPI error handler is invoked if the return value is not MPI_SUCCESS. The default error handler aborts, but this may be changed with by using the MPI_Errhandler_set() function. The predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned instead. Note that MPI does not guarentee that an MPI program can continue past an error. In this implementation, all errors except MPI_ERR_INTERN or MPI_ERR_OTHER should always be recoverable.

In C, the error code is passed as the return value. In FORTRAN, all functions have an parameter ierr which returns the error code. MPI C++ functions do not directly return an error code. However, C++ users may want to use the MPI::ERRORS_THROW_EXCEPTIONS handler. This will throw an MPI::Exception with the corresponding error code. To prevent exceptions from being raised from within C and Fortran code, they will see all error return values as MPI_ERR_PENDING when this handler is chosen. In this implementation, call MPI::throw_exception() to throw the correct exception if this occurs.

MPI_SUCCESS - No error;

MPI_ERR_PENDING - Pending exception;

MPI_ERR_TYPE - Invalid data type;

MPI_ERR_ARG - Invalid pointer.

SEE ALSO

MPI_Type_size (3) MPI_Type_ub (3) MPI_Type_lb (3) MPI_Type_get_true_extent (3) MPI_Type_free (3) MPI_Type_commit (3)

• Lockless
• MPI Documentation
• MPI_Type_extent