This chapter defines the mechanism by which HPF programs may call
non-HPF subprograms as extrinsic procedures. It provides the
information needed to write an explicit interface for a non-HPF
procedure. It defines the means for handling distributed and
replicated data at the interface. This allows the programmer to use
non-Fortran language facilities, perhaps to descend to a lower level of
abstraction to handle problems that are not efficiently addressed by
HPF, to hand-tune critical kernels, or to call optimized libraries.
This interface can also be used to interface HPF to other languages,
such as C.
describes a suggested approach to
supporting the coding of single-processor
``node'' code in single-processor Fortran 90 or in a single-processor
subset of HPF; the idea is that only data that is mapped to a given
physical processor is accessible to it. This allows the programming
of MIMD multiprocessor machines in a single-program multiple-data
(SPMD) style.
(End of advice to implementors.)