比较常用的随机函数

double rnd(unsigned int x){static double c = 262147.0, t, i , r = 34359738365.0/549755813888.0;if (x == 1)r = r * c - (long)(r * c);elsefor (i = 1; i <= -x; i++)r = r * c - (long)(r * c);return r; }