🌱 Random Seed Methods

random-seed-methods.md

🌱 Random Seed Methods

I wanted to see what's out there and here's what I found.

I think this is decent set to study, but I'm mainly interested in the smallest implementation and not worried about if it's computationally random.

@KilledByAPixel (source)

rand = max => Math.sin(++seed)**2 * 1e9 % max

LCG by Jonathan Pugh (@jdspugh) (source)

"longer but faster"

LCG = s => () => (s = Math.imul(741103597, s) >>> 0) / 2 ** 32

prng by anechunaev (source)

const prng = s => (typeof s!=='undefined'&&((l=s%2147483647)<=0&&(l+=2147483646)),((l=l*16807%2147483647)-1)/2147483646);
console.log(prng(seed));		// 0.000023478642127922403
console.log(prng());		// 0.3946133641475936
console.log(prng());		// 0.26681596624368425

Just call it again with seed to start new sequence.

bijou seedRandom (source)

req describes the required argument and what data type it must be. (see source for that)

export let seedRandom = (seed = req("number", "seed")) => {
  var t = (seed += 0x6d2b79f5);
  t = Math.imul(t ^ (t >>> 15), t | 1);
  t ^= t + Math.imul(t ^ (t >>> 7), t | 61);
  return ((t ^ (t >>> 14)) >>> 0) / 4294967296;
};

davidbau seedrandom (source)

<script src="//cdnjs.cloudflare.com/ajax/libs/seedrandom/3.0.5/seedrandom.min.js">
</script>

This has multiple features including using a string as a seed but has a lot more code. See source for example usage.