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by roaur 2170 days ago
Aren't most PRNs made deterministically? LCGs can have huge cycle times and can produce statistically sound random numbers.

I had to look it up and Wikipedia has this statement a bit differently. This one makes Neumann sound funny because his Mid-Square method is a terrible PRN generator.
2 comments
kd5bjo 2170 days ago
> Aren't most PRNs made deterministically?

All pseudorandom numbers are deterministic; that’s what the ‘pseudo-‘ prefix is meant to indicate. There are other kinds of random number generator that observe physical entropy sources instead. Perhaps the most iconic is CloudFlare’s wall of lava lamps[1].

[1] https://blog.cloudflare.com/lavarand-in-production-the-nitty...

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_jal 2170 days ago
History trivia: Cloudflare stole this from SGI, who patented the idea.

https://en.wikipedia.org/wiki/Lavarand

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jgrahamc 2170 days ago
Hardly stole it, literally acknowledged in blog post where we announced this: https://blog.cloudflare.com/lavarand-in-production-the-nitty...

We're not the first ones to do this. Our LavaRand system was inspired by a similar system first proposed[1] and built by Silicon Graphics and patented[2] in 1996 (the patent has since expired).

[1] https://en.wikipedia.org/wiki/Lavarand

[2] https://patents.google.com/patent/US5732138

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_jal 2170 days ago
Calm down.

I'm hardly accusing anyone of any wrong-doing. It is a turn-of-phrase that I'm sure most english-speakers have encountered.

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geoelectric 2170 days ago
It has a very different connotation when you say "I'm stealing..." than it does when you say "you're stealing..." It's only jargon in first-person.

Compare saying "wow, I'm really stupid" when you make a mistake vs. saying "wow, you're really stupid" when they do.

Self-deprecation applied to others is just deprecation.

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kens 2170 days ago
> Cloudflare stole this from SGI, who patented the idea.

Why the accusation that Cloudflare stole this? The patent expired in 2016 and Cloudflare acknowledges SGI on their page.

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ogogmad 2170 days ago
PRNGs are often seeded with a "true" random value, from which they generate a sequence of pseudorandom values. In that case, you actually end up with a hybrid of random and deterministic. An example of this is `/dev/urandom`.
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