alea

Seedable random, an implementation of Johannes Baagøe's Alea algorithm. Mostly a refactored copy paste with the addition of some convenience methods.

Usage

npm install @szydlovski/alea

const Alea = require('@szydlovski/alea');

// will always produce the same numbers for the same seed
new Alea('seed1').next() // 0.061422935919836164
new Alea('seed1').next() // 0.061422935919836164
new Alea('seed2').next() // 0.37036016467027366

const generator = new Alea('seed');
for (let i = 0; i++ < 100;) {
  generator.next();
}
// two ways to clone an existing generator
const clone1 = new Alea().importState(generator.exportState());
const clone2 = generator.clone();

generator.next(); // 0.6304205257911235
clone1.next(); // 0.6304205257911235
clone2.next(); // 0.6304205257911235

API

new Alea([, seed])

Creates a new instance, optionally using a seed, otherwise the current date is used. The seed will be stringified using toString.

Alea.next()

Generates and returns the next random number between 0 and 1.

Alea.random()

Alias of Alea.next.

Alea.exportState()

Returns a copy of the instance's internal state, in the form of an array containing four numbers.

Alea.importState(state)

Imports a given state into the instance. The state should be an array containing four numbers, like the array returned by Alea.exportState. Returns the instance, allowing for chained calls like:

const generator = new Alea().importState(state);

Alea.clone()

Clones the instance. This is the equivalent of:

const clone = new Alea().importState(instance.exportState());

License

Copyright (C) 2010 by Johannes Baagøe baagoe@baagoe.org

Copyright (C) 2020 by Kamil Szydlowski kamil.szydlovski@gmail.com

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.