In article <3f985f2b$1@news.povray.org>,
 "Tom A." <met### [at] yahoocom> wrote:

> I was playing with functions, trying to learn about isosurfaces, when I 
> found something that looked like a "black hole".  But I noticed what 
> looked like some strange shadows or reflections on it, and I cleaned up 
> my code and have some questions on it.

This sounds like typical artifacts of the isosurface intersection 
solving algorithm. If so, it has nothing directly to do with the log() 
function, it is caused by your function having too high of a gradient.
Using higher quality settings (mainly a higher max_gradient) will reduce 
or eliminate these artifacts.


> Can the ?: (conditional) operator be used in a function?

No. The select() function gives the same functionality, however.
http://povray.org/documentation/view/137/#s06_01_03_06


> Can vlength() be used in a function?  (It kept complaining about the "<" 
> symbol on the vector I passed it).

No. Neither can any other vector functions. User defined functions have 
no concept of "vectors". The only way you can get a vector value from 
one is to use a transform, pigment, or spline function, and you can't 
perform mathematical operations on vectors within a function.

A full listing of what you can use in functions is here:
http://povray.org/documentation/view/140/

-- 
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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