Matlab: what happends under the hood when choosing 2 seeds far away with rng

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답변: John D'Errico 2020년 1월 7일
I would like to know more precisely what happends when you choose a custom seed in Matlab (version= '9.5.0.944444 (R2018b)'), e.g.:
rng(101)
From my (limited, nut nevertheless existing) understanding of how pseudo-random number generators work, one can see the seed conceptually as choosing a position in a "very long list of pseudo-random numbers".
Question: lets say, (in my Matlab script), I choose
rng(100)
for my first computation (a sequence of instructions) and then,
rng(1e6)
for my second. Please, note that each time I do some computations it involves generating up to about 300k random numbers (each time).
-> Does that imply that I make sure there is no overlap between the sequence in the "list" starting at 100 and ending around 300k and the one starting at 1e6 and ending at 1'300'000 ? (the idead of "no overlap" comes from the fact since the rng(100) and rng(1e6) are separated by much more than 300k)
i.e. that these are 2 "independent" sequences, (as far as I remember this 'long list' would be generated by a special PRNG algorithm, most likely involing modular arithmetic..?)

답변 (2개)

Fangjun Jiang
Fangjun Jiang 2020년 1월 7일
My understanding of rng(SeedNumber) is that SeedNumber is like an ID (identification number). It gives you the ablity to re-generate the exact same sequence of random numbers in case you need them to compare or re-test. Any seed number will allow you to generate any anount of random numbers.

John D'Errico
John D'Errico 2020년 1월 7일
The "separation" of two seeds is completely irrelevant. Separate them by 1 or 1e6, and they are just different seeds. If you use seeds of 1 and 2, you do NOT get the first and second elements from that long hypothetical list of random numbers.

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