ghost@aladdin.com (L. Peter Deutsch) (11/09/90)
The recursive version of the GCD algorithm probably runs faster than
the iterative one because PostScript interpreters properly optimize
"tail recursion": if the last element of a procedure is another
procedure call, the interpreter does the equivalent of a jump rather
than a call and return. This is an implementation technique that has
been known in the Lisp world for close to 30 years; it is described
explicitly in footnote 4 on p. 41 of the Adobe Red Book.
L. Peter Deutsch :: Aladdin Enterprises :: P.O. box 60264, Palo Alto, CA 94306
ghost@aladdin.com | {uunet,sun,decwrl}!parcplace!aladdin!ghost | (415)329-0264
"Implementation is the sincerest form of flattery."