Mathematica 9 is now available
Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
1998
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 1998

[Date Index] [Thread Index] [Author Index]

Search the Archive

add-on Geometry`Polytopes` : Faces



Although I'm not entirely sure,
it is my impression that the Faces of the polytopes  Icosahedron and
Dodecahedron are not numbered consistently with those of Cube,
Octahedron and Tetrahedron.
For these last three polytopes, the Faces are circulated in such way as
to have a negative sign (outward pointing surface vector) As is, 
        the Icosahedron has all inward pointing surface vectors
(positive signs);
        the Dodecahedron has all *but*one*face* outward pointing signs.


In my view, the Faces[Icosahedron] should produce:

  {{1,2,3},{1,3,4},{1,4,5},{1,5,6},{1,6,2},
   {2,6,11},{2,7,3},{2,11,7},{3,7,8},{3,8,4},
   {4,8,9},{4,9,5},{5,9,10},{5,10,6},{6,10,11},
   {7,11,12},{7,12,8},{8,12,9},{9,12,10},{10,12,11}}

and for the Faces[Dodecahedron] 

{{1,2,3,4,5},{1,5,10,15,6},{1,6,11,7,2},{2,7,12,8,3},{3,8,13,9,4},
 {4,9,14,10,5},{6,15,20,16,11},{7,11,16,17,12},{8,12,17,18,13},
 {9,13,18,19,14},{10,14,19,20,15},{16,20,19,18,17}}

------------------------------------------------------------- My lack of
conviction stems from the way the Dodecahedron (both Vertices & Faces)
is calculated in this package :
                           ^^^^^^^^^^ Dodecahedron/: Faces[Dodecahedron]
:=
        Dodecahedron/: Faces[Dodecahedron] =   
           DualFaces[Icosahedron]       

I would be very surprised if an incorrectness in these functions could
result in the near-correct results as they are currently produced.

Please, correct me if I am wrong.


wouter.
Dr. Wouter L. J. MEEUSSEN
w.meeussen.vdmcc@vandemoortele.be
eu000949@pophost.eunet.be




  • Prev by Date: A bug?
  • Next by Date: running calculations in a batch mode
  • Prev by thread: Re: A simple bug..
  • Next by thread: running calculations in a batch mode