'Returns SVG ellipse element for the Ellipse.
Parameters
scale_factor : float
Multiplication factor for the SVG stroke-width.  Default is 1.
fill_color : str, optional
Hex string for fill color. Default is "#66cc99".'

def _svg(self, scale_factor=1.0, fill_color='#66cc99'):

    from sympy.core.evalf import N
    c = N(self.center)
    (h, v) = (N(self.hradius), N(self.vradius))
    return '<ellipse    fill="{1}"    stroke="#555555"    stroke-width="{0}"    opacity="0.6"    cx="{2}"    cy="{3}"    rx="{4}"    ry="{5}"/>'.format((2.0 * scale_factor), fill_color, c.x, c.y, h, v)
