/**************************************************************
 * Cartographic Projections
 * Lab 1
 * Mark Goadrich
 * CSC 204 - Spring 2008
 **************************************************************/
public class Projection{

    // main method to run the program
    public static void main(String[] args) {
        
        // get latitude phi and longitude lambda from the user
        double phi = Math.toRadians(Double.parseDouble(args[0]));
        double lambda = Math.toRadians(Double.parseDouble(args[1]));

        // Step 1: calculate equirectangular projection
        double x1 = lambda;
        double y1 = phi;

        System.out.println("EQUI: x = " + x1 + ", y = " + y1);

        // Step 2: calculate Mercator projection
        double x2 = lambda;
        double y2 = 0.5 * Math.log((1 + Math.sin(phi)) / (1 - Math.sin(phi)));

        System.out.println("MERC: x = " + x2 + ", y = " + y2);

        // Step 3: calculate Winkel Tripel projection
        double alpha = Math.acos( Math.cos(phi) * Math.cos(lambda / 2));
        double x3 = (lambda * Math.cos( Math.acos( 2 / Math.PI)) + 
                     ((2 * Math.cos(phi) * Math.sin(lambda / 2)) / 
                      (Math.sin(alpha) / alpha))) / 2;
        double y3 = (phi + (Math.sin(phi) / (Math.sin(alpha) / alpha))) / 2;

        System.out.println("WT: x = " + x3 + ", y = " + y3);

        // Step 4: calculate distances between projections
        double em = Math.sqrt(Math.pow(x1 - x2, 2) + Math.pow(y1 - y2, 2));
        double ew = Math.sqrt(Math.pow(x1 - x3, 2) + Math.pow(y1 - y3, 2));
        double mw = Math.sqrt(Math.pow(x3 - x2, 2) + Math.pow(y3 - y2, 2));

        System.out.println("EQUI vs MERC: " + em);
        System.out.println("EQUI vs WT: " + ew);
        System.out.println("MERC vs WT: " + mw);

    }
}