#include <iostream>
#include <math.h>

void main()
{
    float slope, intercept;
    float x1, y1, x2, y2;
    float dx, dy;

    std::cout << "Program f\x94r att kalkylera ekvationen av linje\n";

    std::cout << "Skriv X1: ";
    std::cin >> x1;

    std::cout << "Skriv Y1: ";
    std::cin >> y1;

    std::cout << "Skriv X2: ";
    std::cin >> x2;

    std::cout << "Skriv Y2: ";
    std::cin >> y2;

    dx = x2 - x1;
    dy = y2 - y1;

    slope = dy / dx;
    // y = mx + c
    // intercept c = y - mx
    intercept = y1 - slope * x1; // detsamma som y2 - slope * x2

    std::cout << "Ekvation av linje med slutpunkter (" << x1 << ", " << y1 << ") and (" << x2 << ", " << y2 << ") : Y = ";
    std::cout << slope << "X " << ((intercept < 0) ? ' ' : '+') << intercept << "\n";
}