@thi.ng/dsp/cosine.js

Composable signal generators, oscillators, filters, FFT, spectrum, windowing & related DSP utils

import { TAU } from "@thi.ng/math/api";
import { AGen } from "./agen.js";
const cosine = (freq, amp) => new Cosine(freq, amp);
class Cosine extends AGen {
  constructor(_freq, _amp = 1) {
    super(0);
    this._freq = _freq;
    this._amp = _amp;
    this.calcCoeffs();
  }
  _cos;
  _nxt;
  reset() {
    this.calcCoeffs();
    return this;
  }
  next() {
    const t = this._nxt * this._cos - this._val;
    this._val = this._nxt;
    this._nxt = t;
    return this._val;
  }
  freq() {
    return this._freq;
  }
  setFreq(freq) {
    this._freq = freq;
    this.calcCoeffs();
  }
  amp() {
    return this._amp;
  }
  setAmp(amp) {
    this._amp = amp;
    this.calcCoeffs();
  }
  calcCoeffs() {
    this._nxt = this._amp;
    this._cos = Math.cos(this._freq * TAU) * 2;
    this._val = this._cos * this._amp * 0.5;
  }
}
export {
  Cosine,
  cosine
};