    # File lib/rvg/embellishable.rb, line 30
                def initialize(r, cx=0, cy=0)
                    super()
                    r, cx, cy = Magick::RVG.convert_to_float(r, cx, cy)
                    if r < 0
                        raise ArgumentError, "radius must be >= 0 (#{r} given)"
                    end
                    @primitive = :circle
                    @args = [cx, cy, cx+r, cy]
                    self
                end