span> is the curve’s closest distance to a focal point
and <span class="inline_math">\( \varepsilon \)</span> is the curve’s eccentricity.<span class="intersentencespace"></span> For a circle, <span class="inline_math">\( q=R \)</span> (the radius) and the eccentricity parameter is <span class="inline_math">\( \varepsilon=0 \)</span>.<span class="intersentencespace"></span> For an ellipse, <span class="inline_math">\( q=a(1-\varepsilon) \)</span> and the eccentricity parameter varies between <span class