Re: [boost] [units] Any interest in dimensional analysis for orientational dimensions and Euclidean vectors?

From: Hervé Brönnimann (hervebronnimann_at_[hidden])
Date: 2007-03-12 21:06:43

Ben:  I would add to your reading list the article

A Coordinate Free Geometry ADT (1997)  by Stephen Mann, Nathan Litke,  
Tony DeRose
http://citeseer.ist.psu.edu/191514.html

in which they argue a point that has been made in computer graphics  
over and over, that confusing affine and vector spaces, or even two  
different coordinate systems of a common affine space, leads to hard- 
to-catch errors.  Apparently, this has been a steady source of bugs  
in Computer Graphics as well as any other applications.
--
Herve
On Mar 12, 2007, at 2:04 PM, Ben FrantzDale wrote:
> Anyone interested in this should read up on affine spaces. Absolute
> temperature is an affine point; difference between affine points are
> vectors.The same goes for positions in space or time.
>
> Note that Boost already touches on these ideas in Boost.Date_Time (
> http://www.boost.org/doc/html/date_time.html).
> A Time is an affine point, a Time Duration is a vector. (I believe  
> a Time
> Period could be called a "bound vector".)
>
> See also
> http://en.wikipedia.org/wiki/Affine_space
> http://benfrantzdale.livejournal.com/206467.html – what I wrote  
> about this
> when first heard about affine spaces.
> —Ben