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Re: Conic eccentricity through five points
Posted:
Jul 22, 2013 2:08 PM


> what is the best invariant for a quadric surface?
> <https://en.wikipedia.org/wiki/Conic_section#Eccentric > ity_in_terms_of_...
Actually I was investigating curves of constant crossratio, an important invariant in projective geometry which turned out to be a conic :
(Conjecturing constant crossratio loci of a pencil in E2 ) http://www.ijmsea.com/journal.php?issue=Issue%202&&volume=Volume%202
So next question is to express crossratio of any conic in terms of A,B,C,D and E. Hope it will be interesting to find (calculate) it...
I for one think crossratio is the better invariant of a conic than eccentricity...Do you agree? Anyway, have fun!
Narasimham



