#include<iostream>
using namespace std;
//global, so that we don't have to pass this into every fuction
const int row = 4;
const int col = 4;
//prints a matrix
void printMatrix(double X[][col])
{
	for(int i=0; i<row; i++)
	{
		for(int j=0;j<col; j++)
			cout<<X[i][j]<<" ";
		cout<<endl;
	}
}

//Reads a matrix. Since all arrays pass by reference, these values will be preserved across the function call
void readMatrix(double Y[][col])
{
	cout<<"Enter the matrix, row by row: "<<endl;	
	for(int i=0; i<row; i++)
		for(int j=0;j<col; j++)
			cin>>Y[i][j];
}

// Adds 2 matrices
void addMatrix(double A[][col], double B[][col], double C[][col])
{
	for(int i=0; i<row; i++)
		for(int j=0;j<col; j++)
			C[i][j] = A[i][j] + B[i][j];
}

//multiplies two matrices
//For each position (i,j) in the result matrix, we accumulate the sum of multiplying
//the elements in the ith row of the first matrix with the jth column of the second.
void matMul(double A[][col], double B[][col], double C[][col])
{
	for(int i=0;i<row;i++)
		for(int j =0;j<col;j++)
		{
			C[i][j]=0;
			for(int k =0; k<row; k++)
				C[i][j] = C[i][j] + A[i][k]*B[k][j];
		}

}

int main()
{
	double A[row][col], B[row][col], C[row][col];
	readMatrix(A);
	readMatrix(B);
	addMatrix(A, B, C);
	cout<<"The sum is:"<<endl;
	printMatrix(C);
	
	matMul(A, B, C);
	cout<<"The product is:"<<endl;
	printMatrix(C);
	
	return 0;
}