<Gareth.McCaughan@pobox.com> replied to "Luigi":
+---------------
|   - Integers in Lisp do not overflow. If you multiply
|     1000000000 by 1000000000, you get 1000000000000.
|     (In C++, you are more likely to get 3567587328.)
+---------------

Actually, Luigi, I think Gareth left off a few zeros:  ;-}  ;-}

	> (* 1000000000 1000000000)
	1000000000000000000
	> 

But the basic point is valid. Lisp provides arbitrary-precision
"bignums" (big integers) and arbitrary-precision rational numbers
(a ratio of two integers), so integer arithmetic is neither truncated
at some arbitrary 32- or 64-bit boundary, nor are fractions forced to 
"zero" or floating-point (unless you *tell* them to be):

	> (/ 15.0 25.0)
	0.6
	> (/ 15 25)
	3/5
	> (defvar a 163477937096098716906480)
	A
	> (defvar b 83374438621927341066528)
	B
	> (* a b)
	13629881232457981255816665236528107508034301440
	> (/ a b)
	4278751255/2182181218
	> (gcd a b)
	38206927057296
	> (lcm a b)
	356738483888492081107219718492640
	> (+ 3/5 5/7)
	46/35
	> (+ 46/35 7/11)
	751/385
	> (float 751/385)
	1.9506494
	> (truncate 751/385)
	1 ;			; integer quotient
	366/385			; rational remainder
	>

It also provides floating point numbers (usually in several precisions)
and complex numbers (whose real and imaginary parts may be integers,
rationals, or floats).

	> (* #c(5 2) #c(1 -1))
	#C(7 -3)
	> (+ #c(3/5 1/2) #c(5 2))
	#C(28/5 5/2)
	> (* #c(5.0 2.0) (sqrt -1))
	#C(-2.0 5.0)
	> (imagpart (/ #c(5.0 2.0) (sqrt -1)))
	-5.0
	>


-Rob

-----
Rob Warnock, 31-2-510		<rpw3@sgi.com>
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