Java program to print an identity matrix :
In this tutorial, we will learn how to print one identity matrix using Java progamming language. Identity matrix is a matrix whose digonal elements are 1. Digonal elements starting from top left to right end should be 1 and other elements are 0 of that matrix. For example, following matrix is a identity 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
To print this matrix, we will use two for loops. One inner loop and one outer loop.If the current pointer for both loop is same, print 1 else print 0. Because, for the first line 1 is on matrix[0][0] position. For second line 1 is on matrix[1][1] position etc. Let’s take a look at the program :
Java program :
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
//1
Scanner sc = new Scanner(System.in);
int size;
//2
System.out.println("Enter the size of the matrix :");
size = sc.nextInt();
//3
for (int i = 0; i < size; i++) {
//4
for (int j = 0; j < size; j++) {
//5
if (i == j) {
System.out.print("1 ");
} else {
System.out.print("0 ");
}
}
//6
System.out.println();
}
}
}
Explanation :
The commented numbers in the above program denote the step-number below :
- Create one Scanner object sc to read user-input values . One integer size to store the size of the matrix.
- Ask the user to enter the size of the matrix. Read it and save it in size varibale.
- Run one for loop. This loop will run size number of times.
- Run one inner for loop. This loop will also run size number of times.
- For each iteration, check if i is equal to j or not . If yes, print 1, else print 0.
- Print one new line.
Sample Output :
Enter the size of the matrix :
5
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
Enter the size of the matrix :
3
1 0 0
0 1 0
0 0 1
Enter the size of the matrix :
7
1 0 0 0 0 0 0
0 1 0 0 0 0 0
0 0 1 0 0 0 0
0 0 0 1 0 0 0
0 0 0 0 1 0 0
0 0 0 0 0 1 0
0 0 0 0 0 0 1
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