# File lib/rvg/embellishable.rb, line 29
        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