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Mersenne Twister: a good Pseudo Random Number Generator ( PRNG )
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/* | |
from : http://en.wikipedia.org/wiki/Mersenne_twister | |
*/ | |
let MT | |
let index | |
class PRNG { | |
static setSeed(seed) { | |
// Create a length 624 array to store the state of the generator | |
MT = new Uint32Array(624) | |
index = 0 | |
MT[0] = seed | |
for (let i = 1; i < 624; i++) { | |
MT[i] = 1812433253 * (MT[i - 1] ^ ((MT[i - 1] >> 30) + i)) | |
} | |
} | |
static extractNumber() { | |
if (index === 0) { | |
this.generateNumbers() | |
} | |
let y = MT[index] | |
y = y ^ (y >> 11) | |
y = y ^ ((y << 7) & 2636928640) | |
y = y ^ ((y << 15) & 4022730752) | |
y = y ^ (y >> 18) | |
index = (index + 1) % 624 | |
return y | |
} | |
static generateNumbers() { | |
for (let i = 0; i < 624; i++) { | |
const y = (MT[i] & 0x80000000) + (MT[(i + 1) % 624] & 0x7fffffff) | |
MT[i] = MT[(i + 397) % 624] ^ (y >> 1) | |
if (y % 2 !== 0) { | |
MT[i] = MT[i] ^ 2567483615 | |
} | |
} | |
} | |
static random() { | |
return this.extractNumber() / 0x7fffffff | |
} | |
} | |
PRNG.setSeed(1) | |
export default PRNG | |
/* | |
//usage: | |
PRNG.setSeed( seed );//seed: any int, uint or number | |
PRNG.random(); //returns a pseudo-random value between 0 & 1 | |
*/ |
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