34 lines
1.3 KiB
JavaScript
34 lines
1.3 KiB
JavaScript
"use strict";
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// Adapted from node-fft project by Joshua Wong and Ben Bryan
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// https://github.com/vail-systems/node-fft
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Object.defineProperty(exports, "__esModule", { value: true });
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exports.fftAccurate = void 0;
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const complex_1 = require("./complex");
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const exponent_1 = require("./exponent");
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const fftAccurate = function (vector) {
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const X = [];
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const N = vector.length;
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// Base case is X = x + 0i since our input is assumed to be real only.
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if (N === 1) {
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if (Array.isArray(vector[0])) {
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// If input vector contains complex numbers
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return [[vector[0][0], vector[0][1]]];
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}
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return [[vector[0], 0]];
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}
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// Recurse: all even samples
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const X_evens = (0, exports.fftAccurate)(vector.filter((_, ix) => ix % 2 === 0));
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// Recurse: all odd samples
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const X_odds = (0, exports.fftAccurate)(vector.filter((__, ix) => ix % 2 === 1));
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// Now, perform N/2 operations!
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for (let k = 0; k < N / 2; k++) {
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// t is a complex number!
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const t = X_evens[k];
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const e = (0, complex_1.complexMultiply)((0, exponent_1.exponent)(k, N), X_odds[k]);
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X[k] = (0, complex_1.complexAdd)(t, e);
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X[k + N / 2] = (0, complex_1.complexSubtract)(t, e);
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}
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return X;
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};
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exports.fftAccurate = fftAccurate;
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