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23 Nov 2024 19:04:02 EST (-0500)
  polar zonohedra (Message 1 to 2 of 2)  
From: Russell Towle
Subject: polar zonohedra
Date: 10 Mar 2008 14:00:05
Message: <web.47d5851146de2a24ab112d0c0@news.povray.org>
Polar zonohedra are convex polyhedra bounded by n*(n-1) rhombs, where n is an
integer greater than two. Attached, a zipped archive containing two macros and
a scene file which shows their use.

The two most important parameters or whatever one would call them, are "n" as
defined above, and what I call pitch, a carpentry term applied to the slope of
a rafter. Pitch can be anything from 0 degrees to 90 degrees, although both 0
and 90 give "degenerate" polar zonohedra. It is interesting that when pitch
equals 35.26+ degrees, or arc tan sqrt[ 1/2 ], a polar zonohedron is an
orthogonal and isometric shadow of an n-dimensional cube, a solid shadow, cast
into three dimensions. When pitch is low, polar zonohedra are oblate and like
flying saucers; when pitch is high, polar zonohedra are prolate and like
spindles. If edge length is held fixed and one sends a polar zonohedron through
the whole range of pitch, it has maximal volume if and only if it is an
orthogonal shadow of an n-cube, i.e., when pitch equals arc tan sqrt[ 1/2 ].


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Attachments:
Download 'pov pz macro.zip' (4 KB)

From: alphaQuad
Subject: Re: polar zonohedra
Date: 21 Mar 2008 12:35:00
Message: <web.47e3f1707e2b976b4cb52d730@news.povray.org>
"Russell Towle" <rto### [at] inreachcom> wrote:
> Polar zonohedra are convex polyhedra bounded by n*(n-1) rhombs, where n is an
> integer greater than two. Attached, a zipped archive containing two macros and
> a scene file which shows their use.
>
> The two most important parameters or whatever one would call them, are "n" as
> defined above, and what I call pitch, a carpentry term applied to the slope of
> a rafter. Pitch can be anything from 0 degrees to 90 degrees, although both 0
> and 90 give "degenerate" polar zonohedra. It is interesting that when pitch
> equals 35.26+ degrees, or arc tan sqrt[ 1/2 ], a polar zonohedron is an
> orthogonal and isometric shadow of an n-dimensional cube, a solid shadow, cast
> into three dimensions. When pitch is low, polar zonohedra are oblate and like
> flying saucers; when pitch is high, polar zonohedra are prolate and like
> spindles. If edge length is held fixed and one sends a polar zonohedron through
> the whole range of pitch, it has maximal volume if and only if it is an
> orthogonal shadow of an n-cube, i.e., when pitch equals arc tan sqrt[ 1/2 ].

Made a few changes.
Great spacecraft design @ n7 pitch5
(no maps and should render elsewhere, unlike my other mistakes)


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Attachments:
Download 'zonohedra7.zip' (2 KB)

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