From 38436ba0bb8825d37fa6372cbfabb57ff810fe45 Mon Sep 17 00:00:00 2001 From: Akshay Dubey Date: Wed, 14 Sep 2022 12:27:01 +0530 Subject: [PATCH 1/2] feat: Add Liouville algorithm --- Maths/LiouvilleFunction.js | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) create mode 100644 Maths/LiouvilleFunction.js diff --git a/Maths/LiouvilleFunction.js b/Maths/LiouvilleFunction.js new file mode 100644 index 0000000000..f13916d55d --- /dev/null +++ b/Maths/LiouvilleFunction.js @@ -0,0 +1,25 @@ +/* + * Author: Akshay Dubey (https://github.com/itsAkshayDubey) + * Liouville Function: https://en.wikipedia.org/wiki/Liouville_function + * For any positive integer n, define λ(n) as the sum of the primitive nth roots of unity. + * It has values in {−1, 1} depending on the factorization of n into prime factors: + * λ(n) = +1 if n positive integer with an even number of prime factors. + * λ(n) = −1 if n positive integer with an odd number of prime factors. + */ + +/** + * @function liouvilleFunction + * @description -> This method returns λ(n) of given number n + * returns 1 when number has even number of prime factors + * returns -1 when number has odd number of prime factors + * @param {Integer} number + * @returns {Integer} 1|-1 + */ + +import { PrimeFactors } from './PrimeFactors.js' +export const liouvilleFunction = (number) => { + if (number <= 0) { + throw new Error('Number must be greater than zero.') + } + return PrimeFactors(number).length % 2 === 0 ? 1 : -1 +} From 016942d19c7d37ec143ca5a989987426cd3bb1a8 Mon Sep 17 00:00:00 2001 From: Akshay Dubey Date: Wed, 14 Sep 2022 12:27:17 +0530 Subject: [PATCH 2/2] test: Add unit tests for Liouville algorithm --- Maths/test/LiouvilleFunction.test.js | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) create mode 100644 Maths/test/LiouvilleFunction.test.js diff --git a/Maths/test/LiouvilleFunction.test.js b/Maths/test/LiouvilleFunction.test.js new file mode 100644 index 0000000000..58a79c9cc2 --- /dev/null +++ b/Maths/test/LiouvilleFunction.test.js @@ -0,0 +1,19 @@ +import { liouvilleFunction } from '../LiouvilleFunction' + +const expectedValuesArray = [1, -1, -1, 1, -1, 1, -1, -1, 1, 1, -1, -1, -1, 1, 1, 1, -1, -1, -1, -1, 1, 1, -1, 1, 1, 1, -1, -1, -1, -1, -1, -1, 1, 1, 1, 1, -1, 1, 1, 1, -1, -1, -1, -1, -1, 1, -1, -1, 1, -1, 1, -1, -1, 1, 1, 1, 1, 1, -1, 1, -1, 1, -1, 1, 1, -1, -1, -1, 1, -1, -1, -1, -1, 1, -1, -1, 1, -1, -1, -1, 1, 1, -1, 1, 1, 1, 1, 1, -1, 1, 1, -1, 1, 1, 1, 1, -1, -1, -1, 1] + +describe('Testing liouville function', () => { + for (let i = 1; i <= 100; i++) { + it('Testing for number = ' + i + ', should return ' + expectedValuesArray[i], () => { + expect(liouvilleFunction(i)).toBe(expectedValuesArray[i - 1]) + }) + } + + it('should throw error when supplied negative numbers', () => { + expect(() => { liouvilleFunction(-1) }).toThrow(Error) + }) + + it('should throw error when supplied zero', () => { + expect(() => { liouvilleFunction(0) }).toThrow(Error) + }) +}) pFad - Phonifier reborn

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