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From: jbn@glacier.STANFORD.EDU (John B. Nagle)
Newsgroups: comp.graphics,sci.math
Subject: Re: a torus is almost a quadric
Message-ID: <17855@glacier.STANFORD.EDU>
Date: 19 Nov 88 21:54:52 GMT
References: <149@calmasd.GE.COM>
Reply-To: jbn@glacier.UUCP (John B. Nagle)
Organization: Stanford University
Lines: 16

In article <149@calmasd.GE.COM> pjm@calmasd.UUCP (Pierre Malraison) writes:
>Levin's work on quadrics provides nice ways of getting
>exact solutions for q-q intersection curves in terms
>of square roots of lowish degree polynomials.

     Reference, please. 

     Can this work be extended to deformed superquadrics, along the lines
of Pentland's Supersketch system?  I spent some time trying to determine
whether two deformed superquadrics intersected, and after about a month
was able to reduce it to a messy quadratic programming problem but could 
get no further.  Then I found out that one of Barr's students at UCLA was
trying to solve the problem by using enclosing polyhedra.  This, too, is
messy.  Is there a cleaner solution?

					John Nagle