Determinant of a Matrix in Java

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 = 0

Problem 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.

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//Java Program to Find the Modulus of a

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import java.io.BufferedReader;
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```
import java.io.InputStreamReader;
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```
 
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public class ModulusOfAMatrix {
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    // Function to read array elements and calculate the determinant

    public static void main(String[] args) {

        BufferedReader br= new BufferedReader(new InputStreamReader(System.in));

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        int order=3;
```
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        int[][] matrix=new int[3][3];
```

        System.out.println("Enter the elements of 3x3 matrix");

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        int i,j;
```
```
        for(i=0;i<matrix.length;i++){
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            for(j=0;j<matrix[i].length;j++){

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                try{
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                    matrix[i][j]=Integer.parseInt(br.readLine());

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                }
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                catch(Exception e){
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                    System.out.println("An error occured. Please retry");

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                    return;
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                }
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            }
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        }
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        int determinant,x,y,z;
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        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;
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        System.out.println("The modulus of the given matrix is "+ determinant);

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```
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    }
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}
```

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).

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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

Sanfoundry Global Education & Learning Series – Java Programs.

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