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 14:30:02 EDT (-0400)
  Re: Requesting ideas/opinions for RNG seeding syntax  
From: Phoenex
Date: 27 May 2009 17:00:00
Message: <web.4a1da98638187d7efc80b5930@news.povray.org>
>  However, I will admit that for properly chosen seeds, Alvo is
> probably better than an integer LCG of the same size. This is mostly
> due to the rounding errors that occur with floating point and won't
> occur with integers. This raises an additional issue: that of
> repeatability. Depending on your platform and compiler, you will get
> different rounding errors and therefore different sequences.
> Depending on your application, this may be a showstopper. For
> example, with the exact same source code, I get different values:
>
>  > gcc -O3 -mfpmath=sse -lm -o alvo alvo.c
>  > ./alvo
> 0.149126
>  > gcc -O3 -mfpmath=387 -lm -o alvo alvo.c
>  > ./alvo
> 0.917551
>

Berger is right .

It is very difficult to work with double-precision floating point.

I already knew this, by the many tests carried out.

Depending on the CPU, the compiler or platform, with the same seed
you can get quite different results.

This is why it is very difficult to heuristic analysis.

Only mathematically analysis can get good results.

Alvo prng, in addition to trying to be a good generator of chaos, it still
offers the crazy on the computers of today.


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