In article <3f84f22f$1@news.povray.org>, Anton Sherwood <new### [at] ogrenu> 
wrote:

> > ((6*r - 15)*r + 10)*r*r*r
> 
> Why quintic? 

This function is used in several other places as well, such as the 
recent updates to Perlin noise. It's not something I came up with.


> All we absolutely need is
> 	f(0) = 1
> 	f(1) = f'(1) = f''(1) = 0

No, you also need f'(0) = f"(0) = 0


> for which (1-r)^3 would do; were you also trying to fit the traditional 
> curve?

(1-r)^3 doesn't even remotely resemble the old-style curve. I wasn't 
trying to "fit" it, but I did want something that was somewhat similar.

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