任意实数范围内的随机数生成原理图解

实数区间内随机数产生原理 - 图解分析

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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 1 //产生[low,high]内的任意随机数,并返回
 2 float randnum(float low,float high)
 3 {
 4 int ret_rnd = 0.0;
 5 
 6 float integerf = 0.0;
 7 float driftf = 0.0;
 8 
 9 if (low >= high)
10 {
11 printf("low >= high,rearrange them
");
12 getchar();
13 return;
14 }
15 //---------------------------------------------
16 
17 int integer; //整数部分
18 int decimals; //小数部分
19 
20 float diff = high - low;
21 
22 integer = (int)(high - low); //取整数部分
23 
24 decimals = diff - integer; //取小数部分
25 //---------------------------------------------
26 
27 //1.先计算一个整数偏量值
28 if (integer > 0)
29 
30 integerf= (float)(rand() % integer);
31 
32 else 
33 integerf= 0.0;
34 
35 //2.在整数偏量的基础上进行波动
36 do 
37 {
38 driftf = (float)(rand() / RAND_MAX);//产生小数
39 
40 driftf *= (rand() % 2 == 0 ? 1 : -1);
41 
42 } while ((integerf+driftf<0)||(integerf+driftf>diff));
43 
44  
45 
46 ret_rnd = low+(integerf + driftf) ;
47 
48 return ret_rnd;
49 
50 
51 }
 
 

-------------------任意开区间,闭区间 随机数生成算法---------------

srand((unsigned)time(null));

• (a,b) (rand()%(b-a+1))+a-1
• [a,b) (rand()%(b-a))+a
• (a,b] (rand()%(b-a))+a+1
• [a,b] (rand()%(b-a+1))+a