Java Program to Compute Determinant of a Matrix

This is the Java Program to Find the Modulus of a Matrix.Problem Description

Given a square matrix, find and print the modulus(determinant) of the matrix.
Example:
Matrix:
1 2 3
4 5 6
7 8 9

Output:
Modulus = 0Problem Solution

The algorithm for calculating modulus of 3*3 matrix is
x=(matrix[0][0] * (matrix[1][1] * matrix[2][2] – matrix[1][2] * matrix[2][1]));
y=(matrix[0][1] * (matrix[1][0] * matrix[2][2] – matrix[1][2] * matrix[2][0]));
z=(matrix[0][2] * (matrix[1][0] * matrix[2][1] – matrix[1][1] * matrix[2][0]));

determinant= x – y + z;Program/Source Code

Here is the source code of the Java Program to Find the Modulus of a Matrix. The program is successfully compiled and tested using IDE IntelliJ Idea in Windows 7. The program output is also shown below.

//Java Program to Find the Modulus of a 
 
import java.io.BufferedReader;
import java.io.InputStreamReader;
 
public class ModulusOfAMatrix {
    // Function to read array elements and calculate the determinant
    public static void main(String[] args) {
        BufferedReader br= new BufferedReader(new InputStreamReader(System.in));
        int order=3;
        int[][] matrix=new int[3][3];
        System.out.println("Enter the elements of 3x3 matrix");
        int i,j;
        for(i=0;i<matrix.length;i++){
            for(j=0;j<matrix[i].length;j++){
                try{
                    matrix[i][j]=Integer.parseInt(br.readLine());
                }
                catch(Exception e){
                    System.out.println("An error occured. Please retry");
                    return;
                }
            }
        }
        int determinant,x,y,z;
        x=(matrix[0][0] * (matrix[1][1] * matrix[2][2]
                       - matrix[1][2] * matrix[2][1]));
        y=(matrix[0][1] * (matrix[1][0] * matrix[2][2]
                       - matrix[1][2] * matrix[2][0]));
        z=(matrix[0][2] * (matrix[1][0] * matrix[2][1]
                       - matrix[1][1] * matrix[2][0]));
        determinant= x - y + z;
        System.out.println("The modulus of the given matrix is "+ determinant);
 
    }
}

Program Explanation

1. In function main(), a matrix is entered.
2. Then in variables x, y and z various coefficients are calculated.
3. Finally, the statement (determinant= x – y + z), calculates the determinant and it is displayed.

Time Complexity: O(1).Runtime Test Cases

Case 1 (Simple Test Case):
 
Enter the elements of 3x3 matrix
1
2
3
4
5
6
7
8
9
The modulus of the given matrix is 0
 
Case 2 (Simple Test Case - another example):
 
Enter the elements of 3x3 matrix
12
43
5
23
56
7
45
2
65
The modulus of the given matrix is -19598