The math of random numbers

Message boards : Rosetta@home Science : The math of random numbers

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Profile Feet1st
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Message 49236 - Posted: 30 Nov 2007, 20:41:58 UTC
Last modified: 30 Nov 2007, 20:43:28 UTC

Was reviewing the results gathered by dcdc, discussed here. His first chart happens to report the random number seed used for each work unit.

I understand that a seed is used in a random number generator (RNG), which is basically a formula which uses that starting seed and produces some unique sequence of random numbers. The stream of random numbers produced are used as a starting point for each model run by my machine. Some tasks and machines will use just 1 or a few random numbers from the stream, others will use a 100 or so.

I notice from the list that the seeds assigned to tasks are numbered sequentially. It would seem to me that a better overall distribution of generated random numbers would be produced if the seeds used were random as well. Especially since we are collectively using only a small number of the possible seed values in the work that we do for Rosetta.

Is there anyone that knows enough math to confirm my suspicion above?
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Message 49261 - Posted: 1 Dec 2007, 9:54:18 UTC

You may be correct. However the number generated from seed and seed+1 will normally not exhibit a noticable pattern. So the number of seeds should be more important than the relationship between the seeds for producing good results.
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Message 49353 - Posted: 3 Dec 2007, 15:24:00 UTC

Using Visual Studios probably crude random number generator to generate 10 integers between 0 and 10 inclusive with a seed of 12345 gives:

3 6 8 7 2 8 9 2 9 8

Using a seed 12346 gives:

3 10 4 5 5 9 10 1 4 6

A decent twister or better would be even better.
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Message boards : Rosetta@home Science : The math of random numbers



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