C program to check Identity matrix

Write a C program to read elements in a matrix and check whether matrix is an Identity matrix or not. C program for finding Identity matrix. Logic to check identity matrix in C programming.

Example

Input

```Input elements in matrix:
1 0 0
0 1 0
0 0 1```

Output

`It is an Identity matrix`

Required knowledge

Basic C programming, For loop, Array

What is Identity Matrix?

Identity matrix is a special square matrix whose main diagonal elements is equal to 1 and other elements are 0. Identity matrix is also known as unit matrix.

For checking a matrix A we need to ensure that if i = j then Aij must be equal to 1. Else Aij must be equal to 0. (Where 1 ≤ i ≤ m and 1 ≤ j ≤ n)

Program to check identity matrix

``````/**
* C program to check whether a matrix is Identity matrix or not
*/

#include <stdio.h>
#define SIZE 3 // Matrix size

int main()
{
int A[SIZE][SIZE];
int row, col, isIdentity;

/* Input elements in matrix from user */
printf("Enter elements in matrix of size 3x3: \n");
for(row=0; row<SIZE; row++)
{
for(col=0; col<SIZE; col++)
{
scanf("%d", &A[row][col]);
}
}

/* Check whether it is Identity matrix or not */
isIdentity = 1;
for(row=0; row<SIZE; row++)
{
for(col=0; col<SIZE; col++)
{

if(row==col && A[row][col]!=1)
{
/* If elements of main diagonal is not equal to 1 */
isIdentity = 0;
}
else if(row!=col && A[row][col]!=0)
{
/* If other elements than main diagonal is not equal to 0 */
isIdentity = 0;
}
}
}

/* If it is an Identity matrix */
if(isIdentity == 1)
{
printf("\nThe given matrix is an Identity Matrix.\n");

/*
* Print the Identity matrix
*/
for(row=0; row<SIZE; row++)
{
for(col=0; col<SIZE; col++)
{
printf("%d ", A[row][col]);
}

printf("\n");
}
}
else
{
printf("The given matrix is not Identity Matrix");
}

return 0;
}``````

Output

```Enter elements in matrix of size 3x3:
1 0 0
0 1 0
0 0 1

The given matrix is an Identity Matrix.
1 0 0
0 1 0
0 0 1```

Happy coding 😉