[comp.lang.fortran] External Subprograms in Interface Blocks

peb@cs.purdue.EDU (Paul E. Buis) (09/15/89)

How does one declare the arguments to an external subprogram
in a Fortran 8x interface block?  My only reference to the 
standard is the first edition of Metcalf and Reid.

Suppose one has a subprogram such as:

      function eval(f, x)
      real f, x
      external f
      eval = f(x)
      return
      end

An interface block would look something like:

      interface
      function eval(f, x)
      real f, x
      external f
      end interface

Nowhere does this specify the number and type of the arguments to f.

Has the standard been patched up since Metcalf and Reid's first edition
to cover this sort of thing?