RosettaCodeData/Task/Modular-exponentiation/EchoLisp/modular-exponentiation.echolisp
2016-12-05 23:44:36 +01:00

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599 B
Text

(lib 'bigint)
(define a 2988348162058574136915891421498819466320163312926952423791023078876139)
(define b 2351399303373464486466122544523690094744975233415544072992656881240319)
(define m 1e40)
(powmod a b m)
→ 1527229998585248450016808958343740453059
;; powmod is a native function
;; it could be defined as follows :
(define (xpowmod base exp mod)
(define result 1)
(while ( !zero? exp)
(when (odd? exp) (set! result (% (* result base) mod)))
(/= exp 2)
(set! base (% (* base base) mod)))
result)
(xpowmod a b m)
→ 1527229998585248450016808958343740453059