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Re: [ccp4bb] intersection curve of cone with cylinder
 

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CCP4bb <-- 2008 <-- March 2008 <-- 20 March 2008
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Subject: Input to STFC
From: John R Helliwell jrhelliwell {- at -} GMAIL {- dot -} COM
Date: 2008-03-20 		Next message:
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From: Osman Mirza om {- at -} FARMA {- dot -} KU {- dot -} DK
Date: 2008-03-20


Subject: Re: intersection curve of cone with cylinder
From: Ethan Merritt merritt {- at -} U {- dot -} WASHINGTON {- dot -} EDU
Date: 2008-03-20
On Thursday 20 March 2008 06:45, artem@xtals.org wrote:
> In topology, long time ago, I was taught that these are indeed
> 'intersection curves of surfaces of the second order'. Emphasis on surface
> being second order, not the curve. This was in Russian, which means that
> the English terms may be different. You might also encounter 'intersection
> curves of quadric surfaces'.

That is the name I know them by - "intersection of quadrics".
Very useful for drawing ORTEP plots :-)

The equation for the intersection is very beautiful, with a
lot of symmetry in the equation itself.
But as Artem says it is a pain to solve by hand using algebra.

Ethan





> There are seventeen types of quadric surfaces
> (including real and imaginary ones) and they're a right pain in the neck
> to calculate intersections of.
>
> Artem
>
> > Dear All -
> >
> > if memory serves me right, the intersection curve of
> > a cone with a cylinder (like in a powder diffraction camera) is
> > not an ellipse, but a "Schnittfigur zweiter Ordnung",
> > loosly translated as 'intersection curve of second order'.
> >
> > Is there a correct English term for that type of curve?
> >
> > Thx, br
> > -----------------------------------------------------------------
> > Bernhard Rupp
> > 001 (925) 209-7429
> > +43 (676) 571-0536
> > br@qedlife.com
> > bernhardrupp@sbcglobal.net
> > http://www.ruppweb.org/
> > -----------------------------------------------------------------
> > The hard part about playing chicken
> > is to know when to flinch
> > -----------------------------------------------------------------
> >
>

--
Ethan A Merritt Courier Deliveries: 1959 NE Pacific
Dept of Biochemistry
Health Sciences Building
University of Washington - Seattle WA 98195-7742

CCP4bb navigation

CCP4bb <-- 2008 <-- March 2008 <-- 20 March 2008
Previous message:
Subject: Input to STFC
From: John R Helliwell jrhelliwell {- at -} GMAIL {- dot -} COM
Date: 2008-03-20 		Next message:
Subject: postdoctoral opening
From: Osman Mirza om {- at -} FARMA {- dot -} KU {- dot -} DK
Date: 2008-03-20


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