https://github.com/scijs/periodic-function

List of periodic functions normalized to 0..1 range
https://github.com/scijs/periodic-function

Last synced: about 1 month ago
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List of periodic functions normalized to 0..1 range

• Host: GitHub
• URL: https://github.com/scijs/periodic-function
• Owner: scijs
• Created: 2017-06-22T07:16:50.000Z (over 7 years ago)
• Default Branch: master
• Last Pushed: 2020-10-25T17:00:47.000Z (about 4 years ago)
• Last Synced: 2024-10-31T17:27:54.429Z (about 1 month ago)
• Language: JavaScript
• Size: 24.4 KB
• Stars: 55
• Watchers: 4
• Forks: 4
• Open Issues: 0
• Metadata Files:
  • Readme: readme.md

Awesome Lists containing this project

• awesome-javascript-audio - scijs/periodic-function - oscillator modifiers (sawtooth, square, sine, pulse, step, interpolate, etc) as JS functions, normalized 0..1 (Sound creation / Low frequency oscillators ("LFOs"):)

README

        
# periodic-function [![unstable](https://img.shields.io/badge/stability-unstable-green.svg)](http://github.com/badges/stability-badges) [![Build Status](https://img.shields.io/travis/dfcreative/periodic-function.svg)](https://travis-ci.org/dfcreative/periodic-function)

Collection of periodic functions with period normalized to turns.

## Usage

[![npm install periodic-function](https://nodei.co/npm/periodic-function.png?mini=true)](https://npmjs.org/package/periodic-function/)

```js

const fn = require('periodic-function/')

//π radians

let halfTurn = fn(.5)

//2π radians

let fullTurn = fn(1)

```

## API

### let fn = require('periodic-function/\')

The `fn` takes the amount of turn `t` as the first argument and optional parameters. The list of available functions:

| Signature | Waveform | Meaning |

---|:---:|---|

| sine(t, phase=0) | ![sine](img/sine.png) | `Math.sin` normalized to `0..1` rather than radians `0..2π`. To turn into cos, set `phase=.25`. |

| triangle(t, ratio=0.5) | ![triangle](img/triangle.png) | Triangular waveform with regulated ratio. To turn into sawtooth set `ratio=0` or `ratio=1`. |

| sawtooth(t, inverse=false) | ![sawtooth](img/sawtooth.png) | Edge case of triangular waveform, whether descending or ascending. |

| square(t, ratio=0.5) | ![square](img/square.png) | Rectangular waveform with regulated ratio. To turn into pulse set `ratio=0`. |

| pulse(t, tlr=0) | ![pulse](img/pulse.png) | Delta-pulse, which is `1` at `0` and `0` anywhere else. Pass `tlr` as a precision tolerance, ie. `1e-5`. |

| fourier(t, real, imag?, normalize=false) | ![fourier](img/fourier.png) | [Fourier Series](https://en.wikipedia.org/wiki/Fourier_series) coefficients, ie. harmonics. `0` harmonic is static level, `1`st is base frequency, `2`nd is double base frequency, `3`rd is triple etc. Set `normalize=true` to bring max harmonic to `1`. |

| clausen(t, limit=10) | ![clausen](img/clausen.png) | [Clausen function](https://en.wikipedia.org/wiki/Clausen_function). Pass `limit` to indicate number of iterations, precision/performance tradeoff. |

| step(t, samples) | ![step](img/step.png) | [Step function](https://en.wikipedia.org/wiki/Step_function), picks closest sample value out of a set. |

| interpolate(t, samples) | ![interpolate](img/interpolate.png) | Interpolates between closest values in a sample set. |

| noise(t) | ![noise](img/noise.png) | Repeated sample of noise. |

If you feel like it is not complete list of you know example of a good periodic function, suitable for dsp, welcome to [contribute](https://github.com/dfcreative/periodic-function/issues).

## Related

* [audio-oscillator](https://github.com/audiojs/audio-oscillator)

* [createPeriodicWave](https://developer.mozilla.org/en-US/docs/Web/API/AudioContext/createPeriodicWave)

* [List of periodic functions](https://en.wikipedia.org/wiki/List_of_periodic_functions)

## Credits

© 2017 Dima Yv. MIT License