README.md

interpolateJS

Lagrange interpolation to the rescue!

Intro

InterpolateJS constructs a linear interpolation function p(x) for your provided set of x and y-values, using the Lagrange basis polynomials.

Using .evaluate() you can then provide an x-value to the function, and get an interpolated y-value.

Getting started

Installation:

npm i --save @theiliad/interpolatejs

Usage

import/require:

import { interpolation, fraction } from "@theiliad/interpolatejs/index";

const xValues = [fraction(1, 3), fraction(1, 4), 1];
const yValues = [2, -1, 7];
const pOfx = interpolation(xValues, yValues);

console.log("p(1/3) =", pOfx.evaluate(fraction(1, 3)));
// ==> p(1/3) = 2

In-browser CDN Usage:

<script src="https://unpkg.com/@theiliad/interpolatejs"></script>
<script>
const { interpolation, fraction } = interpolateJS;

const xValues = [fraction(1, 3), fraction(1, 4), 1];
const yValues = [2, -1, 7];

const pOfx = interpolation(xValues, yValues);
console.log(
	"p(1/3) =",
	pOfx.evaluate(
		fraction(1, 3)
	)
);
</script>