001    
002    public class Test{
003            
004            public static void main(String[] args){
005                    
006                    double x = 1.0;
007                    double y = 1.0;
008                    
009                    System.out.println("y,x,      :"+Math.atan2(y,x));
010                    System.out.println("-y,-x,      :"+Math.atan2(-y,-x));
011                    System.out.println("-y,x,      :"+Math.atan2(-y,x));
012                    System.out.println("y,-x,      :"+Math.atan2(y,-x));
013    
014            }
015    }