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https://github.com/edwinm/pringle
Fast pseudorandom number generator
https://github.com/edwinm/pringle
Last synced: 3 days ago
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Fast pseudorandom number generator
- Host: GitHub
- URL: https://github.com/edwinm/pringle
- Owner: edwinm
- License: mit
- Created: 2022-08-27T07:47:50.000Z (about 2 years ago)
- Default Branch: main
- Last Pushed: 2022-09-08T06:49:14.000Z (about 2 years ago)
- Last Synced: 2024-10-30T18:19:10.935Z (9 days ago)
- Language: JavaScript
- Homepage:
- Size: 8.79 KB
- Stars: 0
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# pringle
>Fast pseudorandom number generator
JavaScript adaptation of the pseudorandom number generator
from the 2008 research paper
[Evolving Sub-Grid Turbulence for Smoke Animation [PDF]](https://www.cs.ubc.ca/~rbridson/docs/schechter-sca08-turbulence.pdf)
by H. Schechter and R. Bridson of the The University of British Columbia, Canada.
which in turn uses the research paper [Wavelet Noise [PDF]](https://graphics.pixar.com/library/WaveletNoise/paper.pdf) by Robert L. Cook Tony DeRose
of Pixar Animation Studios for the PRNG.
This algorithm is small, fast and in most cases random enough.
## PRNG
A PRNG (pseudorandom number generator) always generates the same sequence
of random numbers. You can change the sequence by supplying a different seed.
This is very useful if you always want the same sequence of random numbers.
## Install
To install, type in the console:
```shell
npm install pringle
```
## Import
Preferred: load pringle as a JavaScript module
using a bundler like webpack or Rollup:
```javascript
import {Prng} from "pringle";
```
Load pringle dynamically as a JavaScript module
(no bundler needed, like in [demo.js](demo.js)):
```javascript
const {Prng} = await import( "./pringle.js" );
```
## API
### `prng = new Prng(seed);`
Initialise Prng with a seed (any number).
### `const r = prng.rand();`
Returns a floating point number 0 and 1.
This is including 0, excluding 1, so `prng.rand()` can return 0, but will never return 1.
### `const r = prng.rand(max);`
Returns a floating point number between 0 and max.
### `const r = prng.rand(min, max);`
Returns a floating point number between min and max.
### `const i = prng;`
`prng` can be used as an endless iterator of random numbers.
```javascript
let count = 5;
for (const r of prng) {
doSomething(r);
if (count-- == 0) {
break;
}
}
```
### `const i = prng.iter(count);`
Returns an iterable returning `count` random numbers between 0 and 1.
You can use the iterable in a `for` loop like this:
```javascript
for (const r of prng.iter(5)) {
doSomething(r);
}
```
Another example of using the iterator is
generating an array of 5 random integers between 0 and 10:
```javascript
const arr = Array.from(prng.iter(5), (r) => Math.floor(r * 10));
```
### `const r = prng.prng();`
Returns the raw value of the generator, a 32 bit signed integer
(between -2,147,483,648 and 2,147,483,647, inclusive).
Normally, you use `prng.rand()` instead of this function.
## Demo
In the file [demo.js](demo.js), you can see examples of using the API.
You can run it in the console by typing:
```shell
npm run demo
```
## Naming
Pringle is named after the American actress Aileen Pringle (1895-1989).
It's unrelated to some brand of potato-based crisps.
## License
Copyright 2022 [Edwin Martin](https://bitstorm.org/) and released under the [MIT license](LICENSE).