Java求指定精度的开根号运算

原理是二分法不断迭代：

取max为指定值target，min为1，精度要求m；取min和max的中点mid，当midmid>target，把max设定为mid；当midmid<target，把min设定为mid。然后max和min求出新的中间 newMin。

结果就在mid和newMid之间，并不断逼近最终结果，当newMid-mid的绝对值小于m时，结果即为所求

【代码】

package practice;public class Sqrt {public double method(double target, double m) {double min,max,mid,newMid;min = 1;max = target;mid = (min+max) / 2;do {if (mid*mid<target) {min = mid;} else {max = mid;}newMid = mid;mid = (max+min)/2;} while (abs(mid,newMid)>m);return mid;}public double abs(double a, double b) {if (a>b) return a-b;else return b-a;}public static void main(String[] args) {System.out.println(new Sqrt().method(20,0.0001));System.out.println(Math.sqrt(20));}}