The identity matrix is a square matrix of any order in which the diagonal(when the index of row and column are the same) elements are all **1**, and all other elements in the matrix must be **0**. For example,

**[ 1 0 0 ]**

**[ 0 1 0 ]**

**[ 0 0 1 ]**

In the above matrix, we can see that all the diagonal values are **1** and others are **0** so we can say that this is an identity matrix.

To print the identity matrix first we have to initialize an empty array **a[]**. Then we have to accept the values into the variable **rc** from the user to store the number of rows and columns. After that to print the identity matrix using the `for loop`

first assign the value **0** into the variable **i** and perform the sub-step until the condition **'i < row'** becomes false and increment the value of variable **i** in every iteration and in the block of loop we have to perform another loop assign the value 0 into the variable j and perform the sub-step until the condition 'j < col' becomes false and increment the value of variable j in every iteration and in the block of this loop check condition **'i == j'** if true then print **1** otherwise print **0**

**Step 1:** Initialize an empty array **a[]**

**Step 2:** Accept the values into the variable **rc** from the user to store the number of rows and columns

**Step 3:** To print the identity matrix using the `for loop`

first assign the value **0** into the variable **i** and perform the sub-step until the condition **'i < row'** becomes false and increment the value of variable **i** in every iteration

(i) Assign the value **0** into the variable **j** and perform the sub-step until the condition **'j < col'** becomes false and increment the value of variable **j** in every iteration

(a) Check condition **'i == j'** if true then print **1** otherwise print **0**

` ````
<?php
$a = array();
$rc = readline("Enter the number of rows and columns: \n");
echo "The entered matrix is matrix: \n";
for ($i = 0; $i < $rc; $i++) {
for ($j = 0; $j < $rc; $j++) {
if ($i == $j) {
echo "1 ";
} else {
echo "0 ";
}
}
echo "\n";
}
?>
```

Enter the number of rows and columns: 5 The entered matrix is matrix: 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 1