docs: public Point2D.Double calc(double t, Point2D.Double... controlPoints)
      {
          if (controlPoints.length != length)
          {
              throw new IllegalArgumentException("control-points length not "+length);
          }
          double[] cp = convert(controlPoints);
          Point2D.Double point = new Point2D.Double();
          calc(t, point::setLocation, cp);
          return point;
      }