public class Transform2D {
  double m11, m12, m21, m22;

  Transform2D() {
    m11 = m22 = 1.0;
    m12 = m21 = 0.0;
  }

  Transform2D(double a, double b, double c, double d){
    m11 = a;
    m12 = b;
    m21 = c;
    m22 = d;
  }

  public double x(double x, double y){
    return (x*m11)+(y*m12);
  }

  public double y(double x, double y){
    return (x*m21)+(y*m22);
  }
}