n! for xlisp

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1 total messages Started by Strong datatypes for weak minds. Wed, 02 Sep 1992 13:57

#92

Author: Strong datatypes for weak minds.
Date: Wed, 02 Sep 1992 13:57

23 lines
1204 bytes

	kan@dg-rtp.dg.com was nice enough to mail me this, which
	works in XLISP V1.1..2.1 and also traps the negative number 
	case:

		(defun factorial (x)
		  (cond ((> x 1) (* x (factorial (- x 1))))
			((> x -1) 1)
			(t nil)))

	I think the error in my ways is that I was using my CP/M
	laptop where XLISP 1.1 only has integers in the range of
	-32768 to +37767 and it was too late for me to notice
	why (factorial 9) didn't work.

	(Please don't tell me the error in my ways was using CP/M
	in 1992.  I've had my NEC 8400 laptop for ~7 years and can't
	afford anything that small and more powerful on my income...
	otherwise I'd be using Scheme or a Forth-variant like UNTIL.
	Besides, the NEC does words and plays ANSI terminal just fine.)

	Regards,
	rcs

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