Unlimilists

Unlimilists is a way to create unlimited array-like objects. All objects created using Unlimilsts constructor don't store their values but calculate at the moment of accessing the array field.

Getting started

This section explains how to get started with Unlimilists. First of all install it.

npm i unlimilists

Then you can import it.

import {Ulist} from 'unlimilists';

Create a new Ulist by passing a formula to the constructor. You can use n variable in your formula, and it will be changed to current array index.

import {Ulist} from "./index.js";

const ulist = new Ulist('2*n + 1*n^3 - 0.2*n^4');

// calculate element of Ulist with index 10
const tenthElement = ulist[10]; // 2*10 + 10**3 - 0.2*10**4 = -980

API Ulist

constructor

Gets an initial formula which is calculated every time the user tries to get an element by index. The second parameter turns on memoization.

Available operations:

• * - multiply
• + - add
• - - subtract
• / - divide
• ^ - power

Examples

const ulist_1 = new Ulist('2 * (2 - 4)'); // [-4, -4, -4, ....]
const ulist_2 = new Ulist('2*n + 1*n^3 - 0.2*n^4'); // [0, 2.8, 8.8, 16.8, ....]

const ulist_3 = new Ulist('2*n', true); // [0, 2, 4, 6, ...] memoization is turned on

getFormula

Returns an initial formula.

Example

const ulist_1 = new Ulist('2 * (2 - 4)'); // [-4, -4, -4, ....]
const formula = ulist_1.getFormula(); // 2 * (2 - 4)

slice

firstIndex: number
lastIndex: number
step?: number (default = 1)

Returns an array with elements from firstIndex to lastIndex (lastIndex is not included).

Example

const ulist_1 = new Ulist('2 * (2 - 4*n)'); 

const array_1 = ulist_1.slice(0, 5); // [ 4, -4, -12, -20, -28 ]
const array_2 = ulist_1.slice(0, 10, 2); // [ 4, -12, -28, -44, -60 ]

power, divide, multiply, subtract, add

anotherList: Ulist | number;

Modifies the current Ulist's formula.