矩阵主对角线元素和

package test1;
import java.util.Scanner;
public class Test1 
{
    public static void main(String[] args) 
    {           
            double[][] array=new double[4][4];
            System.out.println("请输入一个"+array.length+"*"+array[0].length+"的矩阵：");
            Scanner input = new Scanner(System.in );
            for(int i=0;i<4;i++)
            {
                for(int j=0;j<4;j++)
                {
                    array[i][j]=input.nextDouble();
                }
            }
            System.out.print("主对角线元素和为："+sumMajorDiagonal(array));
    }
    public static double sumMajorDiagonal(double[][] array)
    {
        double sum=0;
        for(int i=0;i<4;i++)
        {
            sum=sum+array[i][i];
        }
        return sum;
    }
}