Linear congruential generator: Difference between revisions

Line 3,245:

=={{header|Scheme}}==

For R7RS Scheme.

{{incomplete|Scheme|Precise which Scheme implementation and version you are using and which Report on the Algorithmic Language

<syntaxhighlight lang="scheme">(import (scheme base)

Scheme version it supports. Due to the implicit function generator definition, this works in Racket, but not in standards-compliant Scheme.}}

(scheme write))

~~<syntaxhighlight~~ ~~lang="scheme">(define ((bsd-rand seed))~~ (set! ~~seed~~ (remainder (+ (* 1103515245 ~~seed~~) 12345) 2147483648)~~) seed~~)

(define ((bsd-rand state))

~~(define~~ ~~((msvcrt-rand seed))~~ (set! ~~seed~~ (remainder (+ (* 214013 ~~seed~~) 2531011) 2147483648~~)) (quotient seed 65536~~))

(set! state (remainder (+ (* 1103515245 state) 12345) 2147483648))

state)

(define ((msvcrt-rand state))

(set! state (remainder (+ (* 214013 state) 2531011) 2147483648))

(quotient state 65536))

; auxiliary function to get a list of 'n random numbers from generator 'r

(define (rand-list r n~~) = (if (zero? n) '() (cons (r) (rand-list r (- n 1))))~~)

(define (rand-list r n)

(if (zero? n) '() (cons (r) (rand-list r (- n 1)))))

(rand-list (bsd-rand 0) 10)

(display (rand-list (bsd-rand 0) 10))

; (12345 1406932606 654583775 1449466924 229283573 1109335178 1051550459 1293799192 794471793 551188310)

(newline)

(~~rand-list~~ (msvcrt-rand 0) 10)

(display (rand-list (msvcrt-rand 0) 10))

; (38 7719 21238 2437 8855 11797 8365 32285 10450 30612)</syntaxhighlight>