// CSE 142, Autumn 2010, Marty Stepp
// This program demonstrates calling some methods from the Math class.
// Math methods use return values rather than directly printing their results.
// This program also demonstrates writing our own methods that return values,
// to perform computations such as line slope and object displacement.

public class MathFun {
    public static void main(String[] args) {
        double tenToTheThird = Math.pow(10, 3);
        double a = Math.pow(10, 3) + 17.6 / Math.sqrt(121.0);
        double r = 7;
        double area = Math.PI * Math.pow(r, 2);
        System.out.println("area is " + area);
        
        System.out.println("10^3 = " + tenToTheThird);
        System.out.println("a = " + a);
        System.out.println("2 to the 5th is " + Math.pow(2, 5));
        
        // test the slope method by calling it, printing result
        double s2 = slope(2, 3, 6, 11);
        System.out.println("The slope is " + s2);
        
        System.out.println(displacement(3.0, 4.0, 5.0));
    }
    
    // Returns the slope of the line between the given points.
    // Assumes that x1 does not equal x2.
    public static double slope(int x1, int y1, int x2, int y2) {
        double dy = y2 - y1;
        double dx = x2 - x1;
        double s = dy / dx;
        return s;
    }
    
    // Computes and returns the change in position (displacement) of a moving
    // body with the given initial velocity v0 in m/s, the given 
    // acceleration a in m/s^2, over the given interval of time t in s.
    public static double displacement(double v0, double a, double t) {
        double result = v0 * t + (double) 1 / 2 * a * Math.pow(t, 2);
        return result;
    }
}