标签：random Java 函数 int float seed 随机 return SeedArray
1.Wichman-Hill 随机数产生器
Excel的随机函数曾用的方法，参考文献：
Wichman, B.A. 和 I.D. Hill，Algorithm AS 183:An Efficient and Portable Pseudo-Random Number Generator，《Applied Statistics》，31，188-190，1982。 Wichman, B.A. 和 I.D. Hill，Building a Random-Number Generator，BYTE，第127-128 页，1987 年 3 月。 Rotz, W. 和 E. Falk，D. Wood 和 J. Mulrow，A Comparison of Random Number Generators Used in Business，发表于 2001 年在佐治亚州亚特兰大市举行的“统计学联合会议”上。
/**
* This is a method of Wichman-Hill random number generator.
*
* @param x
* A seed for generator.
* @return A float random value between [0.0,1.0)
*/
public static float randomWH(java.lang.Integer x) { int[] seed = new int[3];
seed[0] = (171 * x) % 30269;
seed[1] = (172 * (30000 – x)) % 30307;
seed[2] = (170 * x) % 30323; return (x / Math.abs(x))
* (seed[0] / 30269.0F + seed[1] / 30307.0F + seed[2] / 30323.0F) % 1.0F;
}
[[1, 0.26327664], [2, 0.26885703], [3, 0.27443743], [4, 0.28001782], [5, 0.28559822], [6, 0.29117858], [7, 0.296759], [8, 0.30233938], [9, 0.3079198], [10, 0.31350017], [11, 0.31908056], [12, 0.324661], [13, 0.33024135], [14, 0.33582175], [15, 0.34140214]] 平均时间很神奇的都是0-1ms，我的天哪里错了吗？ 
2.RSA 随机数产生器
RSA公钥算法大家都不会不熟悉吧，公认很靠谱的密钥算法。这里就是用了RSA的随机算法。参考：
Wikipedia – RSA problem 其公式：C = (x * exp P) mod N（P是质数，N是两个质数之积）
/**
* This is a method of RSA.
*
* @param x
* A seed for generator.
* @return A float random value between [0.0,1.0)
*/
public static float randomRSA(java.lang.Integer x) { return (float) (x * Math.exp(seedRSA[0]) % seedRSA[1] / seedRSA[1]);
}
3.Java 随机数产生器
Java自带的随机数（就是java.util.Random类），用过的都知道吧。那就直接上代码：
/**
* This is a method of Java random number generator.
*
* @param x
* A seed for generator.
* @return A float random value between [0.0,1.0)
*/
public static float randomJava(java.lang.Integer x) { return (float) (new java.util.Random(1000 * x).nextDouble()); //乘1000来让种子间差距增大
}
[1,0.71018493],[2,0.6234702],[3,0.900814],[4,0.80836606],[5,0.08570986],[6,0.9760623],[7,0.25340614],[8,0.16095819],[9,0.97060144],[10,0.8838867],[11,0.13829768],[12,0.045849733],[13,0.32319355],[14,0.23647882],[15,0.5138226] 平均时间：0-1ms 
4.简单的随机数产生器
又是扫荡Google的战利品，很抱歉忘记出处惹……代码：
/**
* This is a method of basic random generator.
*
* @param x
* A seed for generator.
* @return A float random value between [0.0,1.0)
*/
public static float randomBasic(java.lang.Integer x) {
x = (x << 13) ^ x; return (float) Math
.abs((1.0 - ((x * (x * x * 15731 + 789221) + 1376312589) & 0x7fffffff) / 1073741824.0));
}[1,0.22637305],[2,0.2936329],[3,0.2571852],[4,0.5857607],[5,0.71294135],[6,0.31129658],[7,0.123062514],[8,0.8130556],[9,0.03246965],[10,0.92940825],[11,0.5371662],[12,0.7446079],[13,0.45132604],[14,0.11840015],[15,0.71875775] 平均时间：0-1ms 
5.dotNet 随机数产生器
写了尼玛整整一个类啊我擦，不过是源码转写进来的，也没费什么力气。代码：
(DotNetRandom 类)
package com.awakening.code.random;/**
* This is a random generator which translated from dotNet.
* @Author:AwakeningCode
* @Date: Created in 1:07 2018\1\16 0016
*/public class DotNetRandom { private final static int MBIG = Integer.MAX_VALUE; private final static int MSEED = 161803398; private int inext, inextp; private int[] SeedArray = new int[56]; public DotNetRandom() { this((int) System.currentTimeMillis());
} public DotNetRandom(int Seed) { int ii; int mj, mk;
mj = MSEED - Math.abs(Seed);
SeedArray[55] = mj;
mk = 1; for (int i = 1; i < 55; i++) { /*
* Apparently the range [1..55] is special (Knuth) and so we're
* wasting the 0'th position.
*/
ii = (21 * i) % 55;
SeedArray[ii] = mk;
mk = mj - mk; if (mk < 0)
mk += MBIG;
mj = SeedArray[ii];
} for (int k = 1; k < 5; k++) { for (int i = 1; i < 56; i++) {
SeedArray[i] -= SeedArray[1 + (i + 30) % 55]; if (SeedArray[i] < 0) SeedArray[i] += MBIG; } } inext = 0; inextp = 21; Seed = 1; } /** * Return a new random number [0,1) and reSeed the Seed array. * @return A double [0,1) */ protected double rand() { int retVal; int locINext = inext; int locINextp = inextp; if (++locINext >= 56)
locINext = 1; if (++locINextp >= 56)
locINextp = 1;
retVal = SeedArray[locINext] - SeedArray[locINextp]; if (retVal < 0)
retVal += MBIG;
SeedArray[locINext] = retVal;
inext = locINext;
inextp = locINextp; /*
* Including this division at the end gives us significantly improved
* random number distribution.
*/
return (retVal * (1.0 / MBIG));
}
}package com.awakening.code.random;/**
* @Author:AwakeningCode
* @Date: Created in 1:08 2018\1\16 0016
*/public class TestDotNetRandom { /**
* This is a method of doNet random number generator.
*
* @param x
* A seed for generator.
* @return A float random value between [0.0,1.0)
*/
public static float randomDoNet(java.lang.Integer x) { return (float) new DotNetRandom(1000 * x).rand();
} public static void main(String[] args) { String[] Array = new String[16]; long add = 0; for (int i = 1; i < 16 ; i++){ long startTime = System.currentTimeMillis();
System.out.println("开始测试 randomWH（） ：Generate numbers（1D）"); float result = randomDoNet(i);
System.out.println("本次测试结果：" + result); long endTime = System.currentTimeMillis(); long usingTime = endTime - startTime;
System.out.println("结束测试 randomWH（） ：测试结束，所用时间：" + usingTime + "ms"); add += usingTime; Array[i] = i + "," + result;
} long average = add / 24;
System.out.println("本次测试平均时间：" + average + "ms");
System.out.print("["); for (int i = 0; i < Array.length; i++){
System.out.print("[" + Array[i] + "],");
}
System.out.print("]");
}
}
[1,0.15155746],[2,0.57687163],[3,0.0021858374],[4,0.42750004],[5,0.8528142],[6,0.27812842],[7,0.7034426],[8,0.12875678],[9,0.55407095],[10,0.97938514],[11,0.40469936],[12,0.8300135],[13,0.25532773],[14,0.6806419],[15,0.10595611] 平时时间：0-1ms 
标签：random,Java,函数,int,float,seed,随机,return,SeedArray 来源： https://blog.51cto.com/15076224/2585710
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