At Wed, 10 Aug 2005 23:05:06 +0200, Thomas Chust wrote:
>
> #;2> (expt 10 100)
> 10000000000000110891155767964156222877689497504522960006971153529700550125477736178357726682741211136
The docs already note that expt gives incorrect results for exact
numbers. In the meantime you can use something like this:
(define (power base e) ; like expt but e must be an integer
(define (square x) (* x x))
(if (negative? e)
(/ 1 (power base (- e)))
(let lp ((res 1) (e e))
(cond
((zero? e) res)
((even? e) (* res (square (lp 1 (quotient e 2)))))
(else (lp (* res base) (- e 1)))))))
#;5> (power 10 100)
1000000000000000000000000000000000000000000000000000000000000000000000000000000\0000000000000000000000
--
Alex
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