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From: "Bruno Luong" <b.luong@fogale.fr>
Newsgroups: comp.soft-sys.matlab
Subject: Re: Angle between two vectors
Date: Fri, 28 Dec 2007 18:22:57 +0000 (UTC)
Organization: FOGALE nanotech
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"baris kazar" <mbkazar.nospam@gmail.com> wrote in message
<fl377q$4ip$1@fred.mathworks.com>...

> 
> Hi,-
>  how can we generalize this to 3-D vectors? Think of a 
> plane on 3-D space and you have vectors on this plane. I 
> wanna know the angle between 2 vectors in the range 0-2pi.

The problem is depends on where you look (from above or from
below the plane), you will see the angle between vectors on
this plane reverse the sign (draw them on a transparent
glass and try to look from both sides). In 3D there is
nothing that could tell us whereas looking from one way or
from another is more "correct".

Think like a fish or a bird, not like a man.

Bruno