Periodic waveform functions. Phase t is normalized to [0, 1] — one full turn.
npm install periodic-function
import{sine,square,wavetable}from'periodic-function'sine(0.25)// 1 (peak)square(0.75)// -1 (low)wavetable(null,[0,1,0,0.5])// Float32Array wavetable from Fourier coefficientsAll functions take phase t ∈ [0, 1] as first argument. Values outside [0, 1] wrap correctly.
| Function | Description | |
|---|---|---|
| Waveforms | ||
 | sine(t, phase=0) | Sine wave. phase=0.25 gives cosine. |
 | cosine(t, phase=0) | Cosine wave. Equivalent to sine(t, 0.25). |
 | sawtooth(t) | Descending ramp: 1 at t=0, −1 approaching t=1. For ascending ramp use triangle(t, 0). |
 | square(t, duty=0.5) | Square wave. duty = fraction of period spent high. |
 | triangle(t, ratio=0.5) | Triangle wave. ratio = peak position (0 = ascending ramp, 1 = descending ramp). |
 | trapezoid(t, p1=0.25, p2=0.5, p3=0.75) | Trapezoid wave. Rise ends at p1, fall starts at p2, fall ends at p3. Generalizes square and triangle. |
 | pulse(t, width=0) | Dirac-like pulse: 1 at t=0, 0 elsewhere. width extends the high region. |
 | clausen(t, harmonics=10) | Clausen function: Σ sin(kθ)/k². |
 | noise(t) | Periodic noise — repeating random buffer. |
| Fourier / Wavetable | ||
 | fourier(t, real, imag) | Evaluate one sample from Fourier coefficients. real[k] and imag[k] are cosine/sine amplitudes for harmonic k. Index 0 is DC, 1 is fundamental. |
 | wavetable(real, imag, {size=8192, normalize=true}) | Build a Float32Array wavetable from Fourier coefficients. Used for AudioContext.createPeriodicWave. |
| Lookup | ||
 | interpolate(t, samples) | Linearly interpolate between samples, treating them as one period. |
 | step(t, samples) | Step lookup — nearest sample, no interpolation. |
// Cosine as a phase-shifted sinesine(0,0.25)// 1 (same as cosine(0))// Square wave with 10% duty cyclesquare(0.05,0.1)// 1square(0.15,0.1)// -1// Triangle with peak at 0.25 (asymmetric)triangle(0.25,0.25)// -1 (valley, since peak is at t=0)// Trapezoid as a square with soft edgestrapezoid(t,0.05,0.5,0.55)// Fourier series: pure sinefourier(0.25,null,[0,1])// 1// Wavetable for Web Audio API PeriodicWaveconstreal=newFloat32Array(64)constimag=newFloat32Array(64)for(letk=1;k<64;k+=2)imag[k]=4/(Math.PI*k)// square waveconsttable=wavetable(real,imag)// Float32Array[8192], normalized to ±1- web-audio-api — uses
wavetable()forPeriodicWave - MDN: createPeriodicWave
- List of periodic functions
MIT © Dmitry Iv