In article <pan### [at] iastateedu>,
 Ed Jackson <eja### [at] iastateedu> wrote:

> However, it is the function f_ph which returns this value.  I was just
> curious why it was defined that way, and thought that perhaps the
> definitions of phi and theta were not exactly universal--

There are several conventions in use. Mathematics usually uses a 
different convention (theta = rotation or longitude, phi = elevation or 
latitude) than physics or engineering, which swaps the meanings. 
Sometimes they are even completely reversed, like < r, theta, phi> or 
<r, phi, theta>. You just have to watch out for what system is being 
used.

http://mathworld.wolfram.com/SphericalCoordinates.html


> much like the question of y-up v. z-up or right-handed v. left-handed 
> cartesian coordinate systems.

The former, but not the latter. Right handed and left handed systems are 
both well defined mathematically, it's their usage (like which dimension 
is "up") that is disputed. For example, in the case of computer 2D 
graphics, you already use "y" for height and "x" for side to side, so 
"z" for depth is the simplest way to extend things to 3D.

-- 
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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