63 lines
1.8 KiB
JavaScript
63 lines
1.8 KiB
JavaScript
"use strict";
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Object.defineProperty(exports, "__esModule", {
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value: true
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});
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exports.gammaG = void 0;
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exports.gammaNumber = gammaNumber;
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exports.gammaP = void 0;
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var _number = require("../../utils/number.js");
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var _product = require("../../utils/product.js");
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/* eslint-disable no-loss-of-precision */
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function gammaNumber(n) {
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var x;
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if ((0, _number.isInteger)(n)) {
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if (n <= 0) {
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return isFinite(n) ? Infinity : NaN;
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}
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if (n > 171) {
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return Infinity; // Will overflow
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}
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return (0, _product.product)(1, n - 1);
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}
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if (n < 0.5) {
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return Math.PI / (Math.sin(Math.PI * n) * gammaNumber(1 - n));
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}
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if (n >= 171.35) {
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return Infinity; // will overflow
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}
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if (n > 85.0) {
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// Extended Stirling Approx
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var twoN = n * n;
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var threeN = twoN * n;
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var fourN = threeN * n;
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var fiveN = fourN * n;
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return Math.sqrt(2 * Math.PI / n) * Math.pow(n / Math.E, n) * (1 + 1 / (12 * n) + 1 / (288 * twoN) - 139 / (51840 * threeN) - 571 / (2488320 * fourN) + 163879 / (209018880 * fiveN) + 5246819 / (75246796800 * fiveN * n));
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}
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--n;
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x = gammaP[0];
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for (var i = 1; i < gammaP.length; ++i) {
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x += gammaP[i] / (n + i);
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}
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var t = n + gammaG + 0.5;
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return Math.sqrt(2 * Math.PI) * Math.pow(t, n + 0.5) * Math.exp(-t) * x;
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}
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gammaNumber.signature = 'number'; // TODO: comment on the variables g and p
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var gammaG = 4.7421875;
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exports.gammaG = gammaG;
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var gammaP = [0.99999999999999709182, 57.156235665862923517, -59.597960355475491248, 14.136097974741747174, -0.49191381609762019978, 0.33994649984811888699e-4, 0.46523628927048575665e-4, -0.98374475304879564677e-4, 0.15808870322491248884e-3, -0.21026444172410488319e-3, 0.21743961811521264320e-3, -0.16431810653676389022e-3, 0.84418223983852743293e-4, -0.26190838401581408670e-4, 0.36899182659531622704e-5];
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exports.gammaP = gammaP; |