Program for Identity Matrix in C

Given a square matrix M[r][c] where ‘r’ is some number of rows and ‘c’ are columns such that r = c, we have to check that ‘M’ is identity matrix or not.

Identity Matrix

Identity matrix is also known as Unit matrix of size nxn square matrix where diagonal elements will only have integer value one and non diagonal elements will only have integer value as 0

Like in the given Example below −

$$I1=\begin{bmatrix}1 \end{bmatrix},\\ I2=\begin{bmatrix}1 & 0 \\0 & 1 \end{bmatrix},\\ I3=\begin{bmatrix}1 &0 & 0 \\0 &1 & 0 \\0 &0 &1 \end{bmatrix},\\In=\begin{bmatrix}
1 &0 &0 &...&0 \\
0 &1 &0 &...&0\\
0 &0 &1 &...&0\\
. &. &. &...&.\\
. &. &. &...&.\\
0 &0 &0 &...&1\\
\end{bmatrix} $$

Example

Input: m[3][3] = { {1, 0, 0},
   {0, 1, 0},
   {0, 0, 1}}
Output: yes
Input: m[3][3] == { {3, 0, 1},
   {6, 2, 0},
   {7, 5, 3} }
Output: no

Algorithm

Start
Step 1 -> declare function for finding identity matrix
   int identity(int num)
      declare int row, col
      Loop For row = 0 and row < num and row++
         Loop For col = 0 and col < num and col++
            IF (row = col)
               Print 1
            Else
               Print 0
      End
   End
Step 2 -> In main()
   Declare int size = 4
   Call identity(size)
Stop

Example

#include<stdio.h>
int identity(int num){
   int row, col;
   for (row = 0; row < num; row++){
      for (col = 0; col < num; col++){
         if (row == col)
            printf("%d ", 1);
         else
            printf("%d ", 0);
      }
      printf("\n");
   }
   return 0;
}
int main(){
   int size = 4;
   identity(size);
   return 0;
}

Output