Mathematica 9 is now available
Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2007
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2007

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

Search the Archive

Re: CrossProduct in Spherical Coordinates

  • To: mathgroup at smc.vnet.net
  • Subject: [mg75330] Re: [mg75298] CrossProduct in Spherical Coordinates
  • From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
  • Date: Wed, 25 Apr 2007 05:39:21 -0400 (EDT)
  • References: <200704240726.DAA27495@smc.vnet.net>


On 24 Apr 2007, at 16:26, gogoant06 at yahoo.com.hk wrote:

> Dear all,
>
> I am really new to mathematica and I have met a damn simple problem.
>
> In[1]:=
> <<Calculus`VectorAnalysis`
>
> In[2]:=
> CrossProduct[{1,0,0},{0,1,0},Spherical]
>
> Out[2]=
> {0,0,0}
>
> Why? Isn't the result supposed to be {0,0,1}, even in spherical
> coordinates?
>
> best regards,
> lion
>
>


The poivectornt that has coordinates {0,1,0} in Spherical coordinates  
is simply the vector {0,0,0} in Cartesion coordinates (because the  
first coordinate stands for the "radius" and is 0). Hence the cross  
product of anything with this vector must be 0.
Persumably what you wanted to do was to compute in spherical  
coordiantes the cross product of the vectors which in cartesion  
coordiantes (and not in spherical ones)  are represented as {1,0,0}  
and {0,1,0}? If so, you can do this as follows:


v=CrossProduct[CoordinatesFromCartesian 
[{1,0,0}],CoordinatesFromCartesian[{0,\
1,0}],Spherical]

{1,0,0}

Of course this is the answer in spherical coordinates, so to get it  
in Cartesian cordinates you need to perfomr another coordinate switch:


CoordinatesToCartesian[v]

{0,0,1}

as expected.

Of course it would make more sense to compute it directly in  
Cartesian coordiantes!

Andrzej Kozlowski




  • Prev by Date: Numerical calculation of a double sum (Appell's function F4)
  • Next by Date: Re: Exporting images without white borders
  • Previous by thread: Re: CrossProduct in Spherical Coordinates
  • Next by thread: Re: CrossProduct in Spherical Coordinates