package cal;

import java.util.*;
import java.math.*;

public class Ave { 
	
	//計算平均數
	public static double average(double[] shu){
		double ave=0;
		for(int i=0;i<shu.length;i++){
			ave+=shu[i];
		}
		ave/=shu.length;
		ave=Math.round(ave*1000);
		ave/=1000;
		return ave;
	}
	
	//計算標準差
	public static double getSD(double[] shu,double ave){
		double SD=0;
		for(int i=0;i<shu.length;i++){
			SD+=Math.pow((shu[i]-ave), 2);
		}
		SD/=(shu.length-1);
		SD=Math.sqrt(SD);
		SD=Math.round(SD*1000);
		SD/=1000;
		return SD;
	}
	
	public static void main(String[] args){
		double[] a={1,2,3,4,5,6,7};
		double ave=average(a);
		double SD=getSD(a,ave);
		System.out.println(ave+"   "+SD);
	}
}