public PlaDirection(double p_angle_rad){
  this((long)(Math.cos(p_angle_rad) * 10000),(long)(Math.sin(p_angle_rad) * 10000),false);
}

public PlaDirection ( double p_angle_rad ) { this ( ( long ) ( Math . cos ( p_angle_rad ) * 10000 ) , ( long ) ( Math . sin ( p_angle_rad ) * 10000 ) , false ) ; }
creates a direction whose angle with the x - axis is nearly equal to p_angle this can never be a nan
