Matrix-Matrix Multiplication and Matrix-Vector Multiplication using C++

The Code which is presented below can multiply both Matrix-Matrix as well as Matrix-Vector:

Firstly, the code checks for the size of the matrix and verifies if the Matrix-Matrix or Matrix-Vector pair is compatible for multiplication:

• If the Matrix-Matrix or Matrix-Vector pair are compatible, the code goes to next step where it accepts the data from the user, arranges it in the matrix/vector form and continues with the multiplication.
• If the Matrix-Matrix or Matrix-Vector pair are not compatible, the code informs the user that the given Matrix-Matrix or Matrix-Vector pair are not compatible and it exits the code.

The Code for Both Matrix-Matrix and Matrix-Vector Multiplication is as given below:

//Program that performs Matix Multiplication Operation//

#include<iostream>

int main(){
	int r1, c1, r2, c2, r3, c3;
	//Verifying the correct size of the Matrices//
	std::cout<<"Enter the size of the Matrix A i.e rows * columns"<<std::endl;
	std::cin>>r1>>c1;
	std::cout<<"Enter the size of the Matrix B i.e rows * columns"<<std::endl;
	std::cin>>r2>>c2;
	if(c1==r2){
		std::cout<<"Column of Matrix A == Row of Matrix B, hence, multiplication is possible"<<std::endl;
		}
	else{
		std::cout<<"Column of Matrix A is not equal to Row of Matrix B"<<std::endl;
		std::cout<<"Program Terminated"<<std::endl;
		std::cout<<"Please choose a compatible Matix-Matrix or Matrix-Vector pair."<<std::endl;
		std::exit(0);
		}
	//Reading and Printing the first Matrix//
	double Mat1[r1][c1];
	float el1;
	for(int i = 0; i < r1; ++i){
		for(int j = 0; j < c1; ++j){
			std::cout<<"Enter the Elements of Matrix A:"<<std::endl;
			std::cin>>el1;
			Mat1[i][j] = el1;
			}
		}
	std::cout<<"Matrix A:"<<std::endl;
	for(int i = 0; i < r1; ++i){
		for(int j = 0; j < c1; ++j){
			std::cout<<" "<<Mat1[i][j];
			}std::cout<<" "<<std::endl;
		}
	//Reading and Printing the second Matrix//
	double Mat2[r2][c2];
	float el2;
	for(int i = 0; i < r2; ++i){
		for(int j = 0; j < c2; ++j){
			std::cout<<"Enter the Elements of Matrix B:"<<std::endl;
			std::cin>>el2;
			Mat2[i][j] = el2;
			}
		}
	std::cout<<"Matrix B:"<<std::endl;
	for(int i = 0; i < r2; ++i){
		for(int j = 0; j < c2; ++j){
			std::cout<<" "<<Mat2[i][j];
			}std::cout<<" "<<std::endl;
		}
	//Matrix Multiplication Starts//
	//Initialization of Matix Multiplication (we first initialize the product to zero)//
	//We produce a zeros matrix//
	double MatProd[r1][c2];
	for(int i = 0; i < r1; ++i){
		for(int j = 0; j < c2; ++j){
			MatProd[i][j] = 0;
			}
		}
	//We now replace the zeros in the zeros matrix with product values//
	for(int i = 0; i < r1; ++i){
		for(int j = 0; j < c2; ++j){
			for(int k = 0; k < c1; ++k){
				MatProd[i][j] += Mat1[i][k] * Mat2[k][j];
				}
			}
		}
	std::cout<<"The Product of Matrices:"<<std::endl;	
	r3 = r1;
	c3 = c2;
	for(int i = 0; i < r3; ++i){
		for(int j = 0; j < c3; ++j){
			std::cout<<" "<<MatProd[i][j];
			}std::cout<<" "<<std::endl;
		}
	return 0;
	}

Results:

Matrix-Matrix Multiplication:

Matrix A:

Matrix B:

Product of the Matrices:

Matrix-Vector Multiplication:

Matrix A:

Vector B:

Product of Matrices:

Conclusion:

The Code presented above can multiply both Matrix-Matrix Pair and Matrix-Vector Pair.