wsemi
Version:
A support package for web developer.
201 lines (175 loc) • 6.55 kB
JavaScript
import isNumber from 'lodash/isNumber'
import cstr from './cstr.mjs'
import str2hint from './str2hint.mjs'
let _seed = 0
/**
* 產生偽隨機數
*
* Fork: {@link https://gist.github.com/banksean/300494 MersenneTwister}
*
* Unit Test: {@link https://github.com/yuda-lyu/wsemi/blob/master/test/pseudoRandom.test.mjs Github}
* @memberOf wsemi
* @param {Integer|Number|String} [seed='start1'] 輸入種子seed，給予'start1'為使用初始值1並且隨呼叫次數自增，若為其他則代表使用為指定seed，預設'start1'
* @returns {Number} 回傳隨機數字
* @example
*
* let r
*
* r = pseudoRandom()
* console.log('pseudoRandom', r)
* // => pseudoRandom [0,1)
*
* r = pseudoRandom(123)
* console.log('seed=123', r)
* // => seed=123 0.6964691872708499
*
* r = pseudoRandom(12.3)
* console.log('seed=12.3', r)
* // => seed=12.3 0.8510874302592129
*
* r = pseudoRandom('abc')
* console.log('seed=abc', r)
* // => seed=abc 0.6314232510048896
*
* r = pseudoRandom('abc')
* console.log('seed=abc', r)
* // => seed=abc 0.6314232510048896
*
* r = pseudoRandom('def')
* console.log('seed=def', r)
* // => seed=def 0.9743434484116733
*
* r = pseudoRandom('BH01S123')
* console.log('seed=BH01S123', r)
* // => seed=BH01S123 0.007978770649060607
*
* r = pseudoRandom('BH-01:S-123')
* console.log('seed=BH-01:S-123', r)
* // => seed=BH01S123 0.9579511017072946
*
*/
function pseudoRandom(seed = 'start1') {
//seed
if (seed === undefined) {
seed = new Date().getTime()
}
else if (seed === 'start1') {
_seed++
seed = _seed
}
/* Period parameters */
let N = 624
let M = 397
let MATRIX_A = 0x9908b0df /* constant vector a */
let UPPER_MASK = 0x80000000 /* most significant w-r bits */
let LOWER_MASK = 0x7fffffff /* least significant r bits */
let mt = new Array(N) /* the array for the state vector */
let mti = N + 1 /* mti==N+1 means mt[N] is not initialized */
/* initializes mt[N] with a seed */
let init_genrand = (s) => {
if (isNumber(s)) {
mt[0] = s >>> 0
}
else {
s = cstr(s)
mt[0] = str2hint(s)
}
for (mti = 1; mti < N; mti++) {
let s = mt[mti - 1] ^ (mt[mti - 1] >>> 30)
mt[mti] = (((((s & 0xffff0000) >>> 16) * 1812433253) << 16) + (s & 0x0000ffff) * 1812433253) + mti
/* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
/* In the previous versions, MSBs of the seed affect */
/* only MSBs of the array mt[]. */
/* 2002/01/09 modified by Makoto Matsumoto */
mt[mti] >>>= 0 /* for >32 bit machines */
}
}
// /* initialize by an array with array-length */
// /* init_key is the array for initializing keys */
// /* key_length is its length */
// /* slight change for C++, 2004/2/26 */
// let init_by_array = (init_key, key_length) => {
// let i, j, k
// init_genrand(19650218)
// i = 1; j = 0
// k = (N > key_length ? N : key_length)
// for (; k; k--) {
// let s = mt[i - 1] ^ (mt[i - 1] >>> 30)
// mt[i] = (mt[i] ^ (((((s & 0xffff0000) >>> 16) * 1664525) << 16) + ((s & 0x0000ffff) * 1664525))) +
// init_key[j] + j /* non linear */
// mt[i] >>>= 0 /* for WORDSIZE > 32 machines */
// i++; j++
// if (i >= N) {
// mt[0] = mt[N - 1]; i = 1
// }
// if (j >= key_length) j = 0
// }
// for (k = N - 1; k; k--) {
// let s = mt[i - 1] ^ (mt[i - 1] >>> 30)
// mt[i] = (mt[i] ^ (((((s & 0xffff0000) >>> 16) * 1566083941) << 16) + (s & 0x0000ffff) * 1566083941)) - i /* non linear */
// mt[i] >>>= 0 /* for WORDSIZE > 32 machines */
// i++
// if (i >= N) {
// mt[0] = mt[N - 1]; i = 1
// }
// }
// mt[0] = 0x80000000 /* MSB is 1; assuring non-zero initial array */
// }
/* generates a random number on [0,0xffffffff]-interval */
let genrand_int32 = () => {
let y
let mag01 = new Array(MATRIX_A)
/* mag01[x] = x * MATRIX_A for x=0,1 */
if (mti >= N) { /* generate N words at one time */
let kk
if (mti === N + 1) { /* if init_genrand() has not been called, */
init_genrand(5489)
} /* a default initial seed is used */
for (kk = 0; kk < N - M; kk++) {
y = (mt[kk] & UPPER_MASK) | (mt[kk + 1] & LOWER_MASK)
mt[kk] = mt[kk + M] ^ (y >>> 1) ^ mag01[y & 0x1]
}
for (;kk < N - 1; kk++) {
y = (mt[kk] & UPPER_MASK) | (mt[kk + 1] & LOWER_MASK)
mt[kk] = mt[kk + (M - N)] ^ (y >>> 1) ^ mag01[y & 0x1]
}
y = (mt[N - 1] & UPPER_MASK) | (mt[0] & LOWER_MASK)
mt[N - 1] = mt[M - 1] ^ (y >>> 1) ^ mag01[y & 0x1]
mti = 0
}
y = mt[mti++]
/* Tempering */
y ^= (y >>> 11)
y ^= (y << 7) & 0x9d2c5680
y ^= (y << 15) & 0xefc60000
y ^= (y >>> 18)
return y >>> 0
}
// /* generates a random number on [0,0x7fffffff]-interval */
// let genrand_int31 = () => {
// return (genrand_int32() >>> 1)
// }
// /* generates a random number on [0,1]-real-interval */
// let genrand_real1 = () => {
// return genrand_int32() * (1.0 / 4294967295.0)
// /* divided by 2^32-1 */
// }
/* generates a random number on [0,1)-real-interval */
let genrand = () => {
return genrand_int32() * (1.0 / 4294967296.0)
/* divided by 2^32 */
}
// /* generates a random number on (0,1)-real-interval */
// let genrand_real3 = () => {
// return (genrand_int32() + 0.5) * (1.0 / 4294967296.0)
// /* divided by 2^32 */
// }
// /* generates a random number on [0,1) with 53-bit resolution*/
// let genrand_res53 = () => {
// let a = genrand_int32() >>> 5; let b = genrand_int32() >>> 6
// return (a * 67108864.0 + b) * (1.0 / 9007199254740992.0)
// }
init_genrand(seed)
return genrand()
}
export default pseudoRandom