# Sum of diagonal elements of a matrix in java

Specified a 2D square matrix, calculate totality of components in Principal and Secondary diagonals. For instance, think through the following 4 X 4 given matrix.

``````B00 B01 B02 B03
B10 B11 B12 B13
B20 B21 B22 B23
B30 B31 B32 B33
``````

## Professionally calculate total of diagonals of a matrix

The main diagonal is shaped by the components B00, B11, B22, B33.

1.    Logic for Principal Diagonal: The row-column Logic is row = column.
The inferior diagonal is shaped by the elements B03, B12, B21, B30.

2.    Logic for Inferior Diagonal: The row-column logic is row = numberOfRows – column -1.

Examples :

``````Input :
4
1 2 3 4
4 3 2 1
7 8 9 6
6 5 4 3
Output :
Principal Diagonal: 16
Secondary Diagonal: 20

Input :
3
1 1 1
1 1 1
1 1 1
Output :
Principal Diagonal: 3
Secondary Diagonal: 3
``````

## Example:

``````// program to find
// sum of diagonals
import java.io.*;
public class  Kodlogs{
static void printDiagonalSums(int [][]mat,int n1)

{
int principal1 = 0, secondary1 = 0;
for (int i1 = 0; i1 < n; i1++) {
for (int j1 = 0; j1 < n1; j1++) {

// Logic for principal
if (i1 == j1)
principal1 += mat[i1][j1];
// logic for secondary
// diagonal
if ((i1 + j1) == (n1 - 1))
secondary1 += mat[i1][j1];
}
}

System.out.println("Principal Diagonal:"
+ principal1);

System.out.println("Secondary Diagonal:"
+ secondary1);
}

// Driver code
static public void main (String[] args)
{

int [][]a1 = { { 01, 02, 03, 04 },
{ 05, 06, 07, 08 },
{ 01, 02, 03, 04 },
{ 05, 06, 07, 08 } };

printDiagonalSums(a1, 4);
}
}
``````

Output:

`Principal Diagonal:18`
`Secondary Diagonal:18`
2,760 points
7 4