C++ Program to Perform Matrix Multiplication

Posted in C++ Tutorial

Updated on Oct 06, 2024

By Mari Selvan

👁️ 208 - Views

⏳ 4 mins

💬 1 Comment

C++ 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 C++ 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 C++ code that performs matrix multiplication.

multiplyMatrices.cpp

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#include <iostream>

const int MAX_SIZE = 3;

// Function to perform matrix multiplication
void multiplyMatrices(int firstMatrix[MAX_SIZE][MAX_SIZE], int secondMatrix[MAX_SIZE][MAX_SIZE], int result[MAX_SIZE][MAX_SIZE]) {
  // Initialize the result matrix with zeros
  for (int i = 0; i < MAX_SIZE; ++i) {
    for (int j = 0; j < MAX_SIZE; ++j) {
      result[i][j] = 0;
    }
  }

  // Perform matrix multiplication
  for (int i = 0; i < MAX_SIZE; ++i) {
    for (int j = 0; j < MAX_SIZE; ++j) {
      for (int k = 0; k < MAX_SIZE; ++k) {
        result[i][j] += firstMatrix[i][k] * secondMatrix[k][j];
      }
    }
  }
}

// Function to display a matrix
void displayMatrix(int matrix[MAX_SIZE][MAX_SIZE]) {
  for (int i = 0; i < MAX_SIZE; ++i) {
    for (int j = 0; j < MAX_SIZE; ++j) {
      std::cout << matrix[i][j] << "\t";
    }
    std::cout << std::endl;
  }
}

// Driver program
int main() {
  int firstMatrix[MAX_SIZE][MAX_SIZE] = {
    {1, 2, 3},
    {4, 5, 6},
    {7, 8, 9}
  };
  int secondMatrix[MAX_SIZE][MAX_SIZE] = {
    {9, 8, 7},
    {6, 5, 4},
    {3, 2, 1}
  };
  int result[MAX_SIZE][MAX_SIZE];

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

  // Display the matrices
  std::cout << "First Matrix:" << std::endl;
  displayMatrix(firstMatrix);

  std::cout << "\nSecond Matrix:" << std::endl;
  displayMatrix(secondMatrix);

  std::cout << "\nResult Matrix:" << std::endl;
  displayMatrix(result);

  return 0;
}

💻 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 function multiplyMatrices that takes two matrices (firstMatrix and secondMatrix) and computes their product, storing the result in the result matrix.
It initializes the result matrix with zeros and uses three nested loops to perform the matrix multiplication.
The displayMatrix function is used to display the contents of a matrix.
In the main function, sample input matrices (firstMatrix and secondMatrix) are provided, and the program calls the multiplication function.
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 C++ 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!