code: public SVGPath relativeEllipticalArc(double[] rxy, double ar, double la, double sp, double[] xy) {
      return append(PATH_ARC_RELATIVE).append(rxy[0]).append(rxy[1]).append(ar).append(la).append(sp).append(xy[0]).append(xy[1]);
    }
docs: Elliptical arc curve to the given relative coordinates.
  
  @param rxy radius
  @param ar x-axis-rotation
  @param la large arc flag, if angle &gt;= 180 deg
  @param sp sweep flag, if arc will be drawn in positive-angle direction
  @param xy new coordinates