How to Write C Program for Matrix Multiplication

Understanding matrix multiplication is essential because it is at the core of many mathematical and computational applications. We’ll clarify the mystery related to matrix multiplication in this blog by examining its complexities in the context of the C programming language.

Table of Contents

• Introduction to Matrix Multiplication in C
• Code for Matrix Multiplication in C
• Wrap Up
• FAQs

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Introduction to Matrix Multiplication in C

Matrix multiplication is a fundamental operation in linear algebra, a branch of mathematics that deals with vector spaces and linear mappings between them. Matrices are rectangular arrays of numbers, symbols, or expressions arranged in rows and columns. Multiplying matrices involves combining elements in a systematic way to produce a new matrix.

Let’s consider two matrices, A and B, where A has dimensions m x n (m rows and n columns) and B has dimensions n x p (n rows and p columns). The resulting matrix C, obtained by multiplying A and B, will have dimensions of m x p.

Matrix Representation

Matrices are rectangular arrays of numbers, arranged in rows and columns. 

For example,

Matrix A: m × n matrix (m rows, n columns)

Matrix B: n × p matrix (n rows, p columns)

Multiplication Process

Refer to the below image to understand the concept of matrix multiplication clearly.

So, the elements of the product matrix are calculated by taking the dot product of each row of the first matrix (A) with each column of the second matrix (B).

Here’s a breakdown of how each element is calculated:

– Element in the first row, first column: (6*1 + 7*4) 

– Element in the first row, second column: (6*9 + 7*0) 

– Element in the first row, third column: (6*2 + 7*3) 

– Element in the second row, first column: (5*1 + 2*4) 

– Element in the second row, second column: (5*9 + 2*0) 

– Element in the second row, third column: (5*2 + 2*3) 

Make sure to perform the multiplication systematically, taking the dot product for each element. 

Matrix multiplication is widely used in various fields, including computer graphics, physics, engineering, and machine learning. It forms the foundation for solving systems of linear equations and is a fundamental operation in the manipulation of data in many scientific and computational applications.

Code for Matrix Multiplication in C

Now that you have understood how matrix multiplication works, let us now understand the code for matrix multiplication in the C programming language.

#include <stdio.h>
void multiplyMatrices(int firstMatrix[][10], int secondMatrix[][10], int result[][10], int rowsFirst, int colsFirst, int rowsSecond, int colsSecond);
int main() {
    int firstMatrix[10][10], secondMatrix[10][10], result[10][10], rowsFirst, colsFirst, rowsSecond, colsSecond;
    // Input for the first matrix
    printf("Enter the number of rows and columns for the first matrix: ");
    scanf("%d %d", &rowsFirst, &colsFirst);
    printf("Enter elements of matrix 1:\n");
    for (int i = 0; i < rowsFirst; ++i) {
        for (int j = 0; j < colsFirst; ++j) {
            printf("Enter element a%d%d: ", i + 1, j + 1);
            scanf("%d", &firstMatrix[i][j]);
        }
    }
    // Input for the second matrix
    printf("Enter the number of rows and columns for the second matrix: ");
    scanf("%d %d", &rowsSecond, &colsSecond);
    if (colsFirst != rowsSecond) {
        printf("Error! Number of columns in the first matrix should be equal to the number of rows in the second matrix.\n");
        return 0;
    }
    printf("Enter elements of matrix 2:\n");
    for (int i = 0; i < rowsSecond; ++i) {
        for (int j = 0; j < colsSecond; ++j) {
            printf("Enter element b%d%d: ", i + 1, j + 1);
            scanf("%d", &secondMatrix[i][j]);
        }
    }    multiplyMatrices(firstMatrix, secondMatrix, result, rowsFirst, colsFirst, rowsSecond, colsSecond);
   // Displaying the multiplication result
    printf("\nResultant matrix:\n");
    for (int i = 0; i < rowsFirst; ++i) {
        for (int j = 0; j < colsSecond; ++j) {
            printf("%d  ", result[i][j]);
            if (j == colsSecond - 1)
                printf("\n");
        }
    }
    return 0;
}
void multiplyMatrices(int firstMatrix[][10], int secondMatrix[][10], int result[][10], int rowsFirst, int colsFirst, int rowsSecond, int colsSecond) {
    for (int i = 0; i < rowsFirst; ++i) {
        for (int j = 0; j < colsSecond; ++j) {
            result[i][j] = 0;
        }
    }
    for (int i = 0; i < rowsFirst; ++i) {
        for (int j = 0; j < colsSecond; ++j) {
            for (int k = 0; k < colsFirst; ++k) {
                result[i][j] += firstMatrix[i][k] * secondMatrix[k][j];
            }
        }
    }
}

Output:

Enter the number of rows and columns for the first matrix: 2 2

Enter elements of matrix 1:

Enter element a11: 5

Enter element a12: 5

Enter element a21: 8

Enter element a22: 4

Enter the number of rows and columns for the second matrix: 2 2

Enter elements of matrix 2:

Enter element b11: 8

Enter element b12: 6

Enter element b21: 3

Enter element b22: 7

Resultant matrix:

55  65  

76  76  

Wrap-Up

Understanding and implementing matrix multiplication in C not only enhances a programmer’s ability to optimize algorithms but also enables the development of high-performance applications crucial in industries such as finance, engineering, artificial intelligence, and more. As technology advances, the demand for faster and more efficient computations grows, cementing the significance of matrix multiplication in C as a cornerstone for innovation and progress in diverse industrial domains.

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