In article <opr1pzvldo0x9foi@news.povray.org>,
 Mikael Pohjola <emp### [at] cchutfi> wrote:

> I think you left out the most useful thing: the dot-product is 0 when the 
> two vectors are perpendicular to each other (since the cosine of 90 
> degrees is 0)

I'd say this is even more useful: if the dot product is > 0, the vectors 
point in roughly the same direction (less than 90 degree angle), if it 
is < 0, they point in opposite directions (greater than 90 degree 
angle). And there are many other uses...finding intersections with 
various objects, for example. (the plane intersection equation is little 
more than two dot products)

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: <chr### [at] tagpovrayorg>
http://tag.povray.org/

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