code: public boolean equalsDelta(Coordinate coordinate, double delta) {
  		return null != coordinate &&
  				(Math.abs(this.x - coordinate.x) < delta && Math.abs(this.y - coordinate.y) < delta);
  	}
docs: Comparison using a tolerance for the equality check.
  
  @param coordinate
  coordinate to compare with
  @param delta
  maximum deviation (along one axis, the actual maximum distance is sqrt(2*delta^2))
  @return true