Java Program to Perform Matrix Multiplication

Posted in Java Tutorial

Updated on Oct 30, 2024

By Mari Selvan

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4 mins

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Java Program to Perform Matrix Multiplication

Photo Credit to CodeToFun

Introduction

Matrix multiplication is a fundamental operation in linear algebra and computer science. It involves multiplying two matrices to produce a third matrix.

In this tutorial, we will explore a java program that performs matrix multiplication.

We'll break down the logic step by step and provide a sample implementation.

Example

Let's dive into the java code that performs matrix multiplication.

MatrixMultiplication.java

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public class MatrixMultiplication {

  // Function to perform matrix multiplication
  static void multiplyMatrices(int[][] firstMatrix, int[][] secondMatrix, int[][] resultMatrix) {
    int m = firstMatrix.length;
    int n = firstMatrix[0].length;
    int p = secondMatrix[0].length;

    // Perform matrix multiplication
    for (int i = 0; i < m; ++i) {
      for (int j = 0; j < p; ++j) {
        for (int k = 0; k < n; ++k) {
          resultMatrix[i][j] += firstMatrix[i][k] * secondMatrix[k][j];
        }
      }
    }
  }

  // Function to display a matrix
  static void displayMatrix(int[][] matrix) {
    for (int[] row: matrix) {
      for (int value: row) {
        System.out.print(value + "\t");
      }
      System.out.println();
    }
  }

  // Driver program
  public static void main(String[] args) {
    int[][] firstMatrix = {
      {1, 2, 3},
      {4, 5, 6},
      {7, 8, 9}
    };
    int[][] secondMatrix = {
      {9, 8, 7},
      {6, 5, 4},
      {3, 2, 1}
    };
    int[][] resultMatrix = new int[firstMatrix.length][secondMatrix[0].length];

    // Call the function to perform matrix multiplication
    multiplyMatrices(firstMatrix, secondMatrix, resultMatrix);

    // Display the matrices
    System.out.println("First Matrix:");
    displayMatrix(firstMatrix);

    System.out.println("\nSecond Matrix:");
    displayMatrix(secondMatrix);

    System.out.println("\nResult Matrix:");
    displayMatrix(resultMatrix);
  }
}

Testing the Program

Feel free to replace the sample matrices with your own 3x3 matrices in the main function to test the program with different input.

Output

First Matrix:
1   2   3
4   5   6
7   8   9

Second Matrix:
9   8   7
6   5   4
3   2   1

Result Matrix:
30   24   18
84   69   54
138  114  90

Compiler and run the program to see the result of the matrix multiplication.

How the Program Works

The program defines a class MatrixMultiplication containing a static method multiplyMatrices that takes two matrices (firstMatrix and secondMatrix) and computes their product, storing the result in the resultMatrix.
It uses three nested loops to perform the matrix multiplication based on the given dimensions of the matrices.
The displayMatrix method is used to display the contents of a matrix.
In the main method, sample input matrices (firstMatrix and secondMatrix) are provided, and the program calls the multiplication method.
The program then displays the original matrices and the result matrix.

Understanding the Concept of Matrix Multiplication

Matrix multiplication is defined as follows: given two matrices A (of dimensions m x n) and B (of dimensions n x p), the product matrix C (of dimensions m x p) is obtained by multiplying each element of a row in matrix A by the corresponding element of a column in matrix B and summing up the results.

Conclusion

Matrix multiplication is a powerful operation used in various fields, including graphics, physics simulations, and machine learning.

Understanding the logic behind matrix multiplication and implementing it in java provides a foundational understanding of linear algebra in computer science.

Feel free to experiment with different matrix sizes and values to further explore the capabilities of this program. Happy coding!