# Sum of secondary diagonal of a matrix in Java

In the last tutorial, we learned about the sum of the principal diagonal of a matrix, in this tutorial we will see how to find the sum of the secondary diagonal of a matrix in Java.

Have a look at the below matrix:

A1     A2     A3

B1     B2     B3

C1     C2     C3

Here the principal diagonal is A3 – B2- C1, and our task is to find the sum of these elements.

It has to be noted that the matrix can be of any dimension, though it needs to be a square matrix.

## Java program to find the sum of secondary diagonal of a matrix in Java

Here is how the code will look:

```import java.util.*;
public class test
{
public static void main(String[] args)
{

Scanner sc=new Scanner(System.in);
int arr[][]=new int[3][3];
int dsum=0;
System.out.println("Enter elements in matrix");
for(int i=0;i<=2;i++)
{
for(int j=0;j<=2;j++)
{
arr[i][j]=sc.nextInt();
if(i+j==2)
{
dsum=dsum+arr[i][j];
}
}

}
System.out.println("The sum of secondary principal diagonal is "+dsum);

}
}

```

This will generate the following output:

```Enter elements in matrix
1
2
3
4
5
6
7
8
9
The sum of secondary principal diagonal is 15
```

Hope this helped you out.