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

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\n");

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

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