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MathGroup Archive 1997

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Re: Wrong behavior of CrossProduct

  • To: mathgroup at smc.vnet.net
  • Subject: [mg7997] Re: Wrong behavior of CrossProduct
  • From: Paul Abbott <paul at physics.uwa.edu.au>
  • Date: Wed, 30 Jul 1997 23:57:50 -0400
  • Organization: University of Western Australia
  • Sender: owner-wri-mathgroup at wolfram.com

Sergio Rojas wrote:

>    After playing a little bit with the Mathematica construction for the cross
>    product of two vectors, implemented by the function CrossProduct of the
>    package VectorAnalysis, I strongly believe that CrossProduct do not
>    work properly on Mathematica ... *)
...
> In[1]:= Needs["Calculus`VectorAnalysis`"];
> In[2]:= SetCoordinates[Spherical[r,theta,phi]];
> In[3]:= V = {a1,a2,0};
> In[4]:= U = {0, 0, 1};
> In[5]:=  CrossProduct[U,V]
> Out[5]= {0, 0, 0}
>                  (* Again, wrong result. Same results were obtained on *)

Why do you say this result is wrong?  Your vector U={0, 0,
1}=={r,theta,phi} has zero length.

Cheers,
	Paul 

____________________________________________________________________ 
Paul Abbott                                   Phone: +61-8-9380-2734
Department of Physics                           Fax: +61-8-9380-1014
The University of Western Australia           
Nedlands WA  6907                     mailto:paul at physics.uwa.edu.au 
AUSTRALIA                              http://www.pd.uwa.edu.au/Paul

            God IS a weakly left-handed dice player
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