whrandom / random.js

This is a port of Python's whrandom module, which is a pseudorandom number generator.

That means it creates "random" numbers with a seed, and if you provide the same seed it will create the same set of numbers. This is a common feature in many languages, but not offered by Javascript's Math.random().

This isn't the best random number generator, but the algorithm is very simple.

Mersenne Twister / mersenne.js

Python now prefers the Marsenne Twister. It has some nice features over whrandom (you can read that page to see them).

I've taken a piece of code written by Y. Okada and library-ized it some. It matches the interface of whrandom.

Using it

If you include random.js it will expose one variable: WHRandomStream (mersenne.js exposes MersenneRandomStream). You can also require the module using requirejs or import it in Node (though I haven't provided a pacakge.json), and in both cases the exported object is RandomStream itself (e.g., var RandomStream = require("./random.js");, ditto mersenne.js)

To create a stream, call RandomStream(seed); if no seed is provided then Date.now() is used. To get new random numbers from a stream, simply call the function. All random numbers are between 0 and 1 (but never actually 1), just like Math.random().

MersenneRandomStream instances also have the methods:

.int31(): generates a random number on [0,0x7fffffff]-interval

.real1(): generates a random number on [0,1]-real-interval

.real2(): generates a random number on [0,1)-real-interval (the default)

.real3(): generates a random number on (0,1)-real-interval

.res53(): generates a random number on [0,1) with 53-bit resolution (basically higher resolution version of the default)