POV-Ray : Newsgroups : povray.general : Requesting ideas/opinions for RNG seeding syntax : Re: Requesting ideas/opinions for RNG seeding syntax Server Time
30 Jul 2024 22:17:32 EDT (-0400)
  Re: Requesting ideas/opinions for RNG seeding syntax  
From: "Jérôme M. Berger"
Date: 23 May 2009 18:32:52
Message: <4a187994$1@news.povray.org>
Phoenex wrote:
>>  That's a basic LCG (same as the current POV algorithm) except that
>> it's implemented in floating point. It will have the same
>> shortcomings...
> 
> 

> 
> This algorithm is not a basic LCG.

	Like Warp said, it uses exactly the same equation as an LCG, so 
that makes it an LCG.

> If you Check carefully the tests, you can not find weaknesses or shortcomings.
> In addition it is very, but very fast.
> 
	I just ran a quick test that shows that this algorithm is actually 
3 to 4 times *slower* than Kiss64. See attached source file. Test 
was run like this:

 > gcc -O3 -lm -o random random.c

 > ./random
Empty loop: 0ms
Kiss64 (int): 6622ms
Kiss64 (dbl): 5003ms
Alvo: 21021ms

 > gcc --version
gcc (GCC) 4.2.3 (4.2.3-6mnb1)
Copyright (C) 2007 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There 
is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR 
PURPOSE.

 > uname -a
Linux wraith 2.6.24.7-desktop-2mnb #1 SMP Thu Oct 30 14:31:33 EDT 
2008 x86_64 AMD Athlon(tm) 64 X2 Dual Core Processor 3800+ GNU/Linux


		Jerome
-- 
mailto:jeb### [at] freefr
http://jeberger.free.fr
Jabber: jeb### [at] jabberfr


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