# 2D Array – Scalar Matrix

Write a program to enter elements in the matrix of 4 into 4 order and check whether the matrix is scalar matrix or not( the scalar matrix is basically a square Matrix, whose all off diagonal elements are 0 and on diagonal elements are equal)

```import java.util.Scanner;
class TwoDArray
{
public static void main(String[] args)
{
Scanner in = new Scanner(System.in);
int n = 4;

int a[][] = new int[n][n];
//Input the 2-D Array
System.out.println("Enter all the elements of matrix:");
for (int i = 0; i < n; i++)
{
for (int j = 0; j < n; j++)
{
a[i][j] = in.nextInt();
}
}

//Print the Original 2D Array
System.out.println("Original Matrix:");
for (int i = 0; i < n; i++)
{
for (int j = 0; j < n; j++)
{
System.out.print(a[i][j] + " ");
}
System.out.println("");
}

int flag = 1; //initially think it is a scalar matrix
int x = a[0][0];
//Checking scalar matrix
for (int i = 0; i < n; i++)
{
for (int j = 0; j < n; j++)
{
if(i == j) // condition for left diagonal
{
if(a[i][j]!=x) // if any element is different
{
flag = 0;
break;
}
}
else // for non-diagonal elements
{
if(a[i][j]!=0) // if it is not 0
{
flag = 0;
break;
}
}
}
}

if(flag == 1)
System.out.println("It is a Scalar Matrix");
else
System.out.println("It is not a Scalar Matrix");
}
}```

OUTPUT

Enter all the elements of matrix:
1
0
0
0
0
1
0
0
0
0
1
0
0
0
0
1

Original Matrix:
1 0 0 0
0 1 0 0
0 0 1 0
0 0 0 1

It is a Scalar Matrix