added testMatrix

#include <iostream>

#include <fstream>

#include <string>

#include <iomanip> 

using namespace std;

int main(int argc, char *argv[])

{

    ifstream myfile(argv[1]);

    ifstream myfile1(argv[2]);

    ofstream outfile("res.txt");

    if (myfile.is_open() && myfile1.is_open())

    {

        int arrSize = 0;

        double arr[1001805]; // Ideally this would be a vector, but you said array

        double arr1[1001805]; // Ideally this would be a vector, but you said array

        double res[1001805]; // Ideally this would be a vector, but you said array

        while ( true)

        {

            double x;

            myfile >> x;

            if (myfile.eof())

                break;

            arr[arrSize++] = x;

        }

        arrSize=0;

        while (true)

        {

            double x;

            myfile1 >> x;

            if (myfile1.eof())

                break;

            arr1[arrSize] = x;

            res[arrSize]=arr[arrSize]-arr1[arrSize];

            outfile<<arrSize<<" "<<fixed<<setprecision(20)<< res[arrSize]<<" "<<arr[arrSize]<<" "<<arr1[arrSize]<<"\n";

            arrSize++;

        }

        // I should have closed the file here, but as the program was ending I was lazy	}

    }

        else

        {

            cout << "Unable to open file";

        }

    outfile.close();

    myfile.close();

    myfile1.close();

        return 0;

}