/***
 * Home assignment 01.
 */
public class Task01 {
    /**
     * Function  that solves an quadratic equation (a*x^2 + b*x + c = 0).
     * @param a A squared variable held constant (a*x^2).
     * @param b A variable held constant (b*x).
     * @param c An absolute term (c).
     * @return If equation has 2 roots (x1 and x2), returns the product of them (x1 * x2);
     *         If equation has 1 root (x), returns it (x);
     *         If equation has no roots, returns Double.NaN.
     */
    public static double solveQuadraticEquation(double a, double b, double c) {

        //Calculate the discriminant and initialize d variable.
        double d = b*b-4*a*c ;
        double g = Math.sqrt(d);




        if (d > 0.0) {
            //Calculate the roots and initialize x1 and x2.
            double x1 = (-b + g)/2*a, x2 = (-b - g)/2*a;

            //TODO: add your code here.

            return x1 * x2;
        } else if (d == 0.0) {
            //Calculate the root and initialize x.
            double x = -b/2*a;

            //TODO: add your code here.

            return x;
        } else {
            //Initialize variable x with Double.NaN.
            double x = Double.NaN;

            //TODO: add your code here.

            return x;
        }
    }

    /**
     * Entry-point of the program.
     * This is here so you can test out your code
     * with running this program.
     * @param args Arguments from command-line.
     */
    public static void main(String[] args) {
    	System.out.println("a = 1, b = -5, c = 6: "
    			+ solveQuadraticEquation(1.0, -5.0, 6.0));
    	// should be 6
    	// add some more tests here if needed.
    }
}