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- /*
- Fraction.js v5.0.0 10/1/2024
- https://raw.org/article/rational-numbers-in-javascript/
- Copyright (c) 2024, Robert Eisele (https://raw.org/)
- Licensed under the MIT license.
- */
- const Fraction = require('fraction.js');
-
- // Calculates (a/b)^(c/d) if result is rational
- // Derivation: https://raw.org/book/analysis/rational-numbers/
- function root(a, b, c, d) {
- // Initial estimate
- let x = Fraction(100 * (Math.floor(Math.pow(a / b, c / d)) || 1), 100);
- const abc = Fraction(a, b).pow(c);
- for (let i = 0; i < 30; i++) {
- const n = abc.mul(x.pow(1 - d)).sub(x).div(d).add(x)
- if (x.n === n.n && x.d === n.d) {
- return n;
- }
- x = n;
- }
- return null;
- }
- root(18, 2, 1, 2); // 3/1
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