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From: "Roger Stafford" <ellieandrogerxyzzy@mindspring.com.invalid>
Newsgroups: comp.soft-sys.matlab
Subject: Re: cross product and mat lab
Date: Wed, 6 Feb 2008 16:17:02 +0000 (UTC)
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"Rufus Worrell" <hollywoodbatez@AOL.com> wrote in message <focbdu$hvp
$1@fred.mathworks.com>...
> Hey guys I was wondering I have 3 vectors: a, b, c.  now
> finding the cross product of them on paper is straight
> forward but how would mat lab do a x b .c and a.b x c if a =
> (1,2,3), b = (4,5,6) and c = (7,8,9)
> 
> Thanks!
----------
  The quantities

 (a x b) . c
 (b x c) . a
 (c x a) . b
 a . (b x c)
 b . (c x a)
 c . (a x b)

all give the same value and they can all be evaluated as

 det([a;b;c])

  In your particular example the answer will be zero because a, b, and c are 
linearly dependent, which is to say that they are coplanar.  There is zero 
volume in the parallelepiped formed by them.

Roger Stafford