计算标准差 Exercise07_11

 1 import java.util.Scanner;
 2 /**
 3  * @author 冰樱梦
 4  * 时间：2018年下半年
 5  * 题目：计算标准差
 6  *
 7  */
 8 public class Exercise07_11 {
 9     public static void main(String[] args){
10         Scanner input=new Scanner(System.in);
11         double[] array=new double[10];
12         System.out.println("Enter 10 numbers: ");
13         for(int i=0;i<array.length;i++){
14             array[i]=input.nextDouble();
15         }
16         System.out.printf("%s%.2f\n","The mean is: ",mean(array));
17         System.out.printf("%s%.5f","The standard deviation is: ",deviation(array));
18     }
19     
20     //返回数组的平均值
21     public static double mean(double[] x){
22         double total=0;
23         for(int i=0;i<x.length;i++){
24             total+=x[i];
25         }
26         return total/x.length;
27     }
28     
29     //返回数组的标准差
30     public static double deviation(double[] x){
31         double total=0;
32         for(int i=0;i<x.length;i++){
33             total+=Math.pow((x[i]-mean(x)),2);
34         }
35         return Math.pow(total/(x.length-1), 0.5);
36     }
37 }