http://www.encyclopediaofmath.org/index.php/Descartes_oval   
      
   Where to learn about refraction across cardoide surfaces? that is, case c = 0   
   in above Encyclopedia link? It is stated that Cartesian ovals have been   
   studied well for now a couple of centuries, but no images depict the source,   
   target and the path, or how    
   Snell's Law is obeyed. The Newtonian polar cases are perhaps better known [   
   r*(1 + eps cos(th))]= constant optical path length,but what about the   
   Limaḉons and Cardoides[ constant r/(1 + eps cos(th))]?   
      
   Regards,   
   Narasimham   
      
   --- SoupGate-Win32 v1.05   
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