class Magick::RVG::PathData

def smooth_quadratic_curveto(abs, x, y, *coords)

the coordinates are relative.
true the coordinates are absolute, otherwise
If abs is
Add a smooth quadratic Bezier curveto command. 
def smooth_quadratic_curveto(abs, x, y, *coords)
  @path << sprintf('%s%g,%g ', (abs ? 'T' : 't'), x, y)
  add_points(2, *coords)
end