Pseudo-random numbers/PCG32: Difference between revisions
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{0=>20049, 1=>20022, 2=>20115, 3=>19809, 4=>20005}
</pre>
=={{header|Scheme}}==
{{trans|Ruby}}
<lang Scheme>(import (scheme small) (srfi 33))
(define PCG-DEFAULT-MULTIPLIER 6364136223846793005)
(define MASK64 (- (arithmetic-shift 1 64) 1))
(define MASK32 (- (arithmetic-shift 1 32) 1))
(define-record-type <pcg32-random> (make-pcg32-random-record) pcg32?
(state pcg32-state pcg32-state!)
(inc pcg32-inc pcg32-inc!))
(define (make-pcg32)
(define rng (make-pcg32-random-record))
(pcg32-seed rng 31415926 535897932)
rng)
(define (pcg32-seed rng init-state init-seq)
(pcg32-state! rng 0)
(pcg32-inc! rng
(bitwise-and
(bitwise-ior (arithmetic-shift init-seq 1) 1)
MASK64))
(pcg32-next-int rng)
(pcg32-state! rng (bitwise-and (+ (pcg32-state rng) init-state) MASK64))
(pcg32-next-int rng))
(define (pcg32-next-int rng)
(define xorshifted 0)
(define rot 0)
(define answer 0)
(define oldstate (pcg32-state rng))
(pcg32-state! rng
(bitwise-and
(+ (* oldstate PCG-DEFAULT-MULTIPLIER) (pcg32-inc rng))
MASK64))
(set! xorshifted (bitwise-xor (arithmetic-shift oldstate -18) oldstate))
(set! xorshifted (arithmetic-shift xorshifted -27))
(set! xorshifted (bitwise-and xorshifted MASK32))
(set! rot (bitwise-and (arithmetic-shift oldstate -59) MASK32))
(set! answer (bitwise-ior
(arithmetic-shift xorshifted (- rot))
(arithmetic-shift xorshifted (bitwise-and (- rot) 31))))
(set! answer (bitwise-and answer MASK32))
answer)
(define (pcg32-next-float rng)
(inexact (/ (pcg32-next-int rng) (arithmetic-shift 1 32))))
;; task
(define rng (make-pcg32))
(pcg32-seed rng 42 54)
(let lp ((i 0)) (when (< i 5)
(display (pcg32-next-int rng))(newline)
(lp (+ i 1))))
(newline)
(pcg32-seed rng 987654321 1)
(define vec (make-vector 5 0))
(let lp ((i 0)) (when (< i 100000)
(let ((j (exact (floor (* (pcg32-next-float rng) 5)))))
(vector-set! vec j (+ (vector-ref vec j) 1)))
(lp (+ i 1))))
(let lp ((i 0)) (when (< i 5)
(display i)
(display " : ")
(display (vector-ref vec i))
(newline)
(lp (+ i 1))))
</lang>
{{out}}
<pre>
2707161783
2068313097
3122475824
2211639955
3215226955
0 : 20049
1 : 20022
2 : 20115
3 : 19809
4 : 20005
</pre>
=={{header|Sidef}}==
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