#include <iostream>
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
using namespace std;

void printEquation(int stage);

double s1, n1, s2, n2, y_1, y_2;
double A, B, C, D, numerator, leftDenominator, rightDenominator, degreesFreedom, standardError, tValue, first, second;

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

    if (argc > 1) {
        s1 = atof(argv[1]), n1 = atof(argv[2]), s2 = atof(argv[3]), n2 = atof(argv[4]), y_1 = atof(argv[5]), y_2 = atof(argv[6]);
    }
    else {
        cout << "s1: ";
        cin >> s1;

        cout << "n1: ";
        cin >> n1;

        cout << "s2: ";
        cin >> s2;

        cout << "n2: ";
        cin >> n2;

        cout << "y1: ";
        cin >> y_1;

        cout << "y2: ";
        cin >> y_2;
    }

    cout << "s1 = " << s1 << endl;
    cout << "n1 = " << n1 << endl;
    cout << "s2 = " << s2 << endl;
    cout << "n2 = " << n2 << endl;

    //printEquation(0);

    A = pow(s1, 2) / n1;
    B = pow(s2, 2) / n2;

//  printEquation(1);

    numerator = pow(A + B, 2);

//  printEquation(2);

    A = 1 / ( n1 -1 );
    B = pow(pow(s1, 2) / n1, 2);

    C = 1 / ( n2 - 1 );
    D = pow(pow(s2, 2) / n2, 2);

//  printEquation(3);

    leftDenominator = A * B;
    rightDenominator = C * D;

//  printEquation(4);

    degreesFreedom = numerator / ( leftDenominator + rightDenominator );

    printf("\ndf = %.08f\n", degreesFreedom);

    standardError =  sqrt((pow(s1, 2) / n1) + (pow(s2, 2) / n2));

    printf("SE = %.08f\n\n", standardError);

    cout << "t-value: ";
    cin >> tValue;


    printf("%.04f - %.04f +- %.04f * %.04f\n", y_1, y_2, tValue, standardError);
    first = y_1 - y_2;
    if (first < 0)
        first = abs(first);
    second = tValue * standardError;
    printf("%.04f +- %.08f \n", first, second);
    printf("(%.04f, %.04f)\n", first - second, first + second);
}

void printEquation(int stage) {
    switch (stage) {
    case 0:
        printf("                        / %.0f^2     %.0f^2 \\ ^2\n", s1, s2);
        printf("                       (  ---  +  ---  )\n");
        printf("                        \\ %.0f      %.0f  /\n", n1, n2);
        printf("-----------------------------------------------------------------\n");
        printf(" /    1    \\       /  %.0f   \\ ^2     /    1   \\        /  %.0f  \\ ^2\n", s1, s2);
        printf("(  -------  )  *  (  ----  )   +  (  -------  )  *  ( ----  )\n");
        printf(" \\ %.0f - 1  /       \\  %.0f  /        \\ %.0f - 1  /       \\ %.0f  /\n\n", n1, n2, n1, n2);
        break;
    case 1:
        printf("                        /                   \\ ^2\n");
        printf("                       (  %.4f  +  %.4f  )\n", A, B);
        printf("                        \\                   /\n");
        printf("-----------------------------------------------------------------\n");
        printf(" /    1    \\       /  %.0f   \\ ^2     /    1    \\       /  %.0f  \\ ^2\n", s1, s2);
        printf("(  -------  )  *  (  ----  )   +  (  -------  )  *  ( ----  )\n");
        printf(" \\ %.0f - 1  /       \\  %.0f  /        \\ %.0f - 1  /       \\ %.0f  /\n\n", n1, n2, n1, n2);
        break;
    case 2:
        printf("                         /            \\\n");
        printf("                        (  %.8f  )\n", numerator);
        printf("                         \\            /\n");
        printf("-----------------------------------------------------------------\n");
        printf(" /    1    \\       /  %.0f^2 \\ ^2     /    1    \\       /  %.0f^2 \\ ^2\n", s1, s2);
        printf("(  -------  )  *  (  ----  )   +  (  -------  )  *  (  ----  )\n");
        printf(" \\ %.0f - 1  /       \\  %.0f  /        \\ %.0f - 1  /       \\  %.0f  /\n\n", n1, n2, n1, n2);
        break;
    case 3:
        printf("                         /            \\\n");
        printf("                        (  %.8f  )\n", numerator);
        printf("                         \\            /\n");
        printf("-----------------------------------------------------------------\n");
        printf("(  %.4f  )  *  (  %.4f  )   +  (  %.4f  )  *  (  %.4f  )\n\n", A, B, C, D);
        break;
    case 4:
        printf("                         /            \\\n");
        printf("                        (  %.8f  )\n", numerator);
        printf("                         \\            /\n");
        printf("-----------------------------------------------------------------\n");
        printf("             (  %.8f  )   +  (  %.8f  )\n\n", leftDenominator, rightDenominator);
        break;
    case 5:
        break;
    }
}