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Re: A Question about Combinatorica

  • To: mathgroup at smc.vnet.net
  • Subject: [mg104791] Re: [mg104765] A Question about Combinatorica
  • From: Murray Eisenberg <murray at math.umass.edu>
  • Date: Tue, 10 Nov 2009 05:58:50 -0500 (EST)
  • Organization: Mathematics & Statistics, Univ. of Mass./Amherst
  • References: <200911091044.FAA05613@smc.vnet.net>
  • Reply-to: murray at math.umass.edu

This does not require the Combinatorica package, at least in current 
versions of Mathematica:

   pts={{0.,0.,1.},{0.181636,0.559017,0.809017},
        {-0.769421,0.559017,0.309017},{-0.769421,-0.559017,-0.309017},
        {0.181636,-0.559017,-0.809017}};

   Permutatations[pts];  (* suppress output *)

   Length[Permutations[pts]]
120

What do you mean "similarities"?  You have 5 different points (as you 
can check by comparing the Length of Union[pts]).  So there are exactly 
120 (== 5! ) distinct permutations of those 5 objects.

Marwa Abd El-Wahaab wrote:
> Dear Sir
> 
> I have a question about  permutations of 5 points in 3D space .
> 
> These 5 points are on the surface of a sphere of radius =1.
> 
> These points are:
>  { {0., 0., 1.},  {0.181636, 0.559017, 0.809017},  {-0.769421,
> 0.559017, 0.309017}, {-0.769421, -0.559017, -0.309017}, {0.181636,
> -0.559017, -0.809017} }
> 
> My question:
> 
> What are all possible permutations for these 5 points ?
> 
> What are the permutations after delete similarities?
> 
> 
> I need your reply
> 
> Thanks
> 
> Marwa Ali
> 
> 

-- 
Murray Eisenberg                     murray at math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305


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