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Matrix multiplication

I never understand the code of matrix multiplication. Can anyone help me out?

21st Jan 2017, 6:02 AM
Anjan Chandra Paudel
Anjan Chandra Paudel - avatar
1 Resposta
+ 2
The main concept is that matrix multiplication works only when number of columns of first matrix is equal to the number of rows of the second matrix. I have also included the comments in the below code. Hope you understand. If you have any doubts please reply me back. I will more than happy to solve. #include <iostream> using namespace std; int main() { int a[10][10], b[10][10], mult[10][10], r1, c1, r2, c2, i, j, k; cout << "Enter rows and columns for first matrix: "; cin >> r1 >> c1; cout << "Enter rows and columns for second matrix: "; cin >> r2 >> c2; // If column of first matrix in not equal to row of second matrix, // ask the user to enter the size of matrix again. while (c1!=r2) { cout << "Error! column of first matrix not equal to row of second."; cout << "Enter rows and columns for first matrix: "; cin >> r1 >> c1; cout << "Enter rows and columns for second matrix: "; cin >> r2 >> c2; } // Storing elements of first matrix. cout << endl << "Enter elements of matrix 1:" << endl; for(i = 0; i < r1; ++i) { for(j = 0; j < c1; ++j) { cout << "Enter element a" << i + 1 << j + 1 << " : "; cin >> a[i][j]; } // Storing elements of second matrix. cout << endl << "Enter elements of matrix 2:" << endl; for(i = 0; i < r2; ++i) for(j = 0; j < c2; ++j) { cout << "Enter element b" << i + 1 << j + 1 << " : "; cin >> b[i][j]; } // Initializing elements of matrix mult to 0. for(i = 0; i < r1; ++i) for(j = 0; j < c2; ++j) { mult[i][j]=0; } // Multiplying matrix a and b and storing in array mult. for(i = 0; i < r1; ++i) for(j = 0; j < c2; ++j) for(k = 0; k < c1; ++k) { mult[i][j] += a[i][k] * b[k][j]; } // Displaying the multiplication of two matrix. cout << endl << "Output Matrix: " << endl; for(i = 0; i < r1; ++i) for(j = 0; j < c2; ++j) { cout << " " << mult[i][j]; if(j == c2-1) cout << endl; } return 0; }
31st Mar 2017, 5:40 AM
Vishnu ks
Vishnu ks - avatar