import java.util.*;

//***********************************************************************************
/** Class to return iterate of 2D Circle map function.<br>
*/
//***********************************************************************************

public class Circle2DFunction extends Map2DFunction {
      double X,Y;

      Circle2DFunction() {      

            nParameters=3;    
            a = new double[nParameters];    
            aDefault = new double[nParameters];
            aDefault[0]=1.0;
            aDefault[1]=0.5;
            aDefault[2]=0.6144;      
            title = "Circle Map";
            xminDefault=0.0;
            xmaxDefault=1.0;
            yminDefault=-3.14159; 
            ymaxDefault=3.14159;
            winding=0;
            total=0;
            showWinding=true;
      }      
                       
      
//***********************************************************************************      
/** iterates the map function
* @param x input value
* @return iterated value
*/
//***********************************************************************************
      public void iterate(double[] x) {                       

            X = x[0];
            Y = x[1];

            x[1] = a[1]*Y-a[0]*Math.sin(2*Math.PI*X); 
            x[0] = mod(X+a[2]+x[1]/(2*Math.PI));
            
            x[2]=X;
            x[3]=Y;
      }      

//***********************************************************************************      
/** iterates the tangent space to the map
* @param x input value and returns updated values
* x[0] and x[1] contain the new values of X and Y
* x[2] and x[3] contain the previous values
* @param t value of tangent vector (updated by iteration)
*/
//***********************************************************************************
      public void iterateTangent(double[] x, double[] t) {
            X = t[0];
            Y = t[1];
            t[1] = a[1]*Y-2*Math.PI*a[0]*Math.cos(2*Math.PI*x[0])*X;
            t[0] = X+t[1]/(2*Math.PI); 
      }              

//***********************************************************************************               
}