Computational Intrinsic Functions Up: Intrinsic and Library Previous: Notation

System Inquiry Intrinsic Functions

In a multi-processor implementation, the processors may be arranged in an implementation-dependent multi-dimensional processor array. The system inquiry functions return values related to this underlying machine and processor configuration, including the size and shape of the underlying processor array. NUMBER_OF_PROCESSORS returns the total number of processors available to the program or the number of processors available to the program along a specified dimension of the processor array. PROCESSORS_SHAPE returns the shape of the processor array.

The values returned by the system inquiry intrinsic functions remain constant for the duration of one program execution. Thus, NUMBER_OF_PROCESSORS and PROCESSORS_SHAPE have values that are restricted expressions and may be used wherever any other Fortran 90 restricted expression may be used. In particular, NUMBER_OF_PROCESSORS may be used in a specification expression.

The values of system inquiry functions may not occur in initialization expressions, because they may not be assumed to be constants. In particular, HPF programs may be compiled to run on machines whose configurations are not known at compile time.

Note that the system inquiry functions query the physical machine, and have nothing to do with any PROCESSORS directive that may occur.
Thu Jul 21 17:05:43 CDT 1994