1 package com.company;
2
3
4 import org.junit.Test;
5
6 public class Lesson3_2 {
7
8 /**
9 * @Description: 计算大于1的正整数之平方根
10 * @param n-待求的数, deltaThreshold-误差的阈值, maxTry-二分查找的最大次数
11 * @return double-平方根的解
12 */
13 public static double getSqureRoot(int n, double deltaThreshold, int maxTry) {
14
15 if (n <= 1) {
16 return -1.0;
17 }
18
19 double min = 1.0, max = (double)n;
20 for (int i = 0; i < maxTry; i++) {
21 double middle = (min + max) / 2;
22 double square = middle * middle;
23 double delta = Math.abs((square / n) - 1);
24 if (delta <= deltaThreshold) {
25 return middle;
26 } else {
27 if (square > n) {
28 max = middle;
29 } else {
30 min = middle;
31 }
32 }
33 }
34
35 return -2.0;
36
37 }
38
39 @Test
40 public void Test1()
41 {
42 int number = 10;
43 double squareRoot = Lesson3_2.getSqureRoot(number, 0.000001, 10000);
44 if (squareRoot == -1.0) {
45 System.out.println("请输入大于1的整数");
46 } else if (squareRoot == -2.0) {
47 System.out.println("未能找到解");
48 } else {
49 System.out.println(String.format("%d的平方根是%f", number, squareRoot));
50 }
51 }
52 }
