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How to multiply two matrices

Hasham Ahmad

Overview

To multiply two matrices, the rows of the first matrix must be equal to the number of columns of the second matrix. Matrix multiplication is a dot product. Let’s understand this with the help of a diagram.

Matrix multiplication

Example

#include <iostream>
using namespace std;

#define size 3      // number of rows  and column

void matixMultiplicaion(int MatrixA[][size], int MatrixB[][size]) {
    int result[size][size];  // declare result matrix 3 X 3
    for (int i = 0; i < size; i++) { // handle rows
        for (int j = 0; j < size; j++) { // handle column
            result[i][j] = 0; // assign default value
            for (int k = 0; k < size; k++) { // compute dot product of matrix
                result[i][j] += MatrixA[i][k] * MatrixB[k][j];
            }
            cout << result[i][j] << "  "; // print the resultan matrix 
        }
        cout << endl;
    }
}
int main() {
   
 int MatrixA[size][size] = { // declare Matrix A 3x3
            {1, 1, 1},
            {2, 2, 2},
            {3, 3, 3},    
    };
 int MatrixB[size][size] = { // declare Matrix B 3X3
            {1, 1, 1},
            {2, 2, 2},
            {3, 3, 3},   
    };
   
 /*    since it is square matrix the row and 
       column size are same so we do not need to check
       the row and column are equal or not
 */
    matixMultiplicaion(MatrixA, MatrixB);
 
    return 0;
}

Explanation

  • Line 6: We implement the function matixMultiplicaion.
  • Line 21–30: We declare two matrices, MatrixA and MatrixB.
  • Line 36: We call the matixMultiplicaion function.

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c++
matrix
communitycreator
multiplication
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