Pure Procedures

For example (in Fortran 95 and Full HPF),

    PURE REAL FUNCTION F(x,y)
    PURE SUBROUTINE G(x,y,z)

Side effect free:

• no external I/O or ALLOCATE,
• don't change global program state (global data),
• have PURE attribute,
• intrinsic / ELEMENTAL functions are pure,
• allowed in FORALL and pure procedures,

PURE procedures can be executed in parallel.

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