题目:求一个3*3矩阵对角线元素之和
package cn.ls.lanqiao;
import java.util.*;
public class Test29 {
public static void main(String[] args) {
double[][] a = new double[3][3];
double sum1 = 0;
double sum2 = 0;
Scanner sc = new Scanner(System.in);
for (int i = 0; i < a.length; i++) {
for (int j = 0; j < a[i].length; j++) {
a[i][j] = sc.nextDouble();
if (i == j) {
sum1 += a[i][j];
}
if (a.length - 1 - i == j) {
sum2 += a[i][j];
}
}
}
System.out.println("矩阵对角线之和分别是:" + sum1 + "和" + sum2);
}
}