√2在范围(1,2)之间,初中思路:去根号。,比较办法是:1*1< 2 < 2*2,用二分的思路,维护左右区间一起平方一大一小,而逼近的取值mid = (L+R)/2,然后而每次比较用midmid和2比较。
精度:精度也要用平方!!!用abs(midmid - 2和0.01*0.01)
int main()
{
// 根号2平方是2
double l = 1;
double r = 2;
double mid = 0;
while (1)
{
mid = (l + r) / 2;
if (mid*mid < 2 && abs(mid*mid- 2) >= 0.0001)
// 小了扩左
l = mid;
else if (mid*mid > 2 && abs(mid*mid - 2) >= 0.0001)
r = mid;
if (abs(mid*mid - 2) < 0.0001)
{
cout << l << " " << r << endl;
cout << (l + r ) / 2 << endl;
break;
}
}
return 0;
}