11–20 of 52 posts
My personal favorite RNG is the logistical map. x_{n+1} = 4x_n(1-x_n). There is no hidden seed beyond the current output. Thus if you have a scientific calculator that lets you refer to the value on screen then you can rig it into an RNG. Seeing a simple, non-programmable machine "misbehave" and act random melts my mind a little.
My personal favorite RNG is the logistical map. x_{n+1} = 4x_n(1-x_n). There is no hidden seed beyond the current output. Thus if you have a scientific calculator that lets you refer to the value on screen then you can rig it into an RNG. Seeing a simple, non-programmable machine "misbehave" and act random melts my mind a little.
2. The dice roll example is not uniform distribution, I think this is a common pitfall when generating random integers of a range. `randomNumber % 6` results in a slight bias towards 0 and 1, since 2^31 % 6 == 2, there are more numbers in the range [0, 2^31-1] that map to 0 and 1 than those that map to 2...5. To make it uniform, for example, you should always discard if `randomNumber < 2` and regenerate another number for use.
[0] https://blog.cloudflare.com/randomness-101-lavarand-in-produ...
[1] https://blog.cloudflare.com/lavarand-in-production-the-nitty...
1. You don't turn PRNG into "true" RNGs simply by picking seeds from environmental randomness. The seed is just the initial state, as long as the output is generated by a deterministic algorithm, by definition it's a PRNG. At the very best you can make a CSPRNG, but not a "true" RNG. 2. The dice roll example is not uniform distribution, I think this is a common pitfall when generating random integers of a range. `ran…
Just out of layman's curiosity, what would be the problem or difficulty of somehow connecting a more compact type of radio telescope that detects some level of cosmic background radiation and hooking that up to a computer. Would this not be a guaranteed way of generating truly random numbers for any need flawlessly? I know that serious radio telescopes cost way more than any random person could afford to pay but I've…
Any stochastic data source may not (and almost certainly isn't) evenly distributed--it'll probably follow some normal distribution. Your PRNG that reads from your telescope would need to compensate for this. As far as using radiation to generate random numbers, check out https://www.fourmilab.ch/hotbits/
It reminds me of a story from Cryptonomicon in which a character mentions a secretary grabbing randomly spun number balls from a tumbling device while blindfolded (if I remember the objects right) and not liking the results when she had to write them down because they didn't look random enough to her, so she starts peeking and slightly "correcting", and thus ruins a number of one-time pads
Just out of layman's curiosity, what would be the problem or difficulty of somehow connecting a more compact type of radio telescope that detects some level of cosmic background radiation and hooking that up to a computer. Would this not be a guaranteed way of generating truly random numbers for any need flawlessly? I know that serious radio telescopes cost way more than any random person could afford to pay but I've…
Any stochastic data source may not (and almost certainly isn't) evenly distributed--it'll probably follow some normal distribution. Your PRNG that reads from your telescope would need to compensate for this. As far as using radiation to generate random numbers, check out https://www.fourmilab.ch/hotbits/
The Mersenne-Twister approach should certainly not be studied anymore, even if some popular old libraries still use it. It fell long out of favor, is too slow, and not good enough. Modern PRNG's can be tested with Dieharder, TestU01 or STS and benchmarked. This article only talks about primitive old LCG's (not any good one) or MT.
When you say Mersenne-Twister isn't good enough, what are the other shortcomings apart from speed? It seems that even modern versions of Python are continuing to use it...
Even a truncated 128-bit LCG has far better properties.
See https://www.pcg-random.org/index.html
The homepage might come across as a a little overzealous (for example ChaCha quality listed as good rather than excellent), but generally has good points.
Just out of layman's curiosity, what would be the problem or difficulty of somehow connecting a more compact type of radio telescope that detects some level of cosmic background radiation and hooking that up to a computer. Would this not be a guaranteed way of generating truly random numbers for any need flawlessly? I know that serious radio telescopes cost way more than any random person could afford to pay but I've…
1. You don't turn PRNG into "true" RNGs simply by picking seeds from environmental randomness. The seed is just the initial state, as long as the output is generated by a deterministic algorithm, by definition it's a PRNG. At the very best you can make a CSPRNG, but not a "true" RNG. 2. The dice roll example is not uniform distribution, I think this is a common pitfall when generating random integers of a range. `ran…