get-parabola

This module was created for have ability to receive quadratic fit coeffs for the condition like a*x^2 + bx + c by different ways.

Install

$ yarn add get-parabola

Usage

import Coeffs from 'get-parabola';

// Or any separate method of the class if necessary:
import { by2Points } from 'get-parabola';

So, you can use methods below

• by2Points // object like ({ k, b })
• getLineBy2Points // function like x => number
• by3Points // object like ({ a, b, c, error: string|null })
• getLineBy3Points // function like x => number or null
• byLeastSquaresApproximation // object like ({ a, b, c })
• getBrokenLineByPoints // function like x => number
• getLineByLeastSquaresApproximation // function like x => number

by2Points

const coeffs = Coeffs.by2Points([
  { x: 1, y: 1 },
  { x: 2, y: 2 }
]);

console.log(coeffs);
// { k: 1,
//   b: 0 }

getLineBy2Points

const lineFn = Coeffs.getLineBy2Points([
  { x: 1, y: 1 },
  { x: 2, y: 2 },
]);

console.log(lineFn(5));
// 5

by3Points

// CASE 1:
const coeffs = Coeffs.by3Points({
  x1: 1, y1: 1,
  x2: 2, y2: 4,
  x3: 3, y3: 9,
});

// CASE 2: And argument could be an Array like [{ x, y }] (but 3 points!)
const coeffs2 = Coeffs.by3Points([
  { x: 1, y: 1 },
  { x: 2, y: 4 },
  { x: 3, y: 9 },
]);

console.log(coeffs);
console.log(coeffs2);
// { a: 1,
//   b: 0,
//   c: 0,
//   error: null }
// But error could be string as explanation, check !error before use result.

getLineBy3Points

const lineFn = Coeffs.getLineBy3Points([
  { x: 1, y: 1 },
  { x: 2, y: 4 },
  { x: 3, y: 9 },
]);

console.log(lineFn(5));
// 25

byLeastSquaresApproximation

const coeffs = Coeffs.byLeastSquaresApproximation([
  { x: 4, y: 4 },
  { x: 5, y: 5 },
  { x: 6, y: 6 },
  { x: 10, y: 7 },
  { x: 12, y: 8 },
  { x: 15, y: 9 },
]);

console.log(coeffs);
// { a: -0.015889095754389806,
//   b: 0.7155842733545066,
//   c: 1.744177344577082 }

getLineByLeastSquaresApproximation

const lineFn = Coeffs.getLineByLeastSquaresApproximation([
  { x: 4, y: 4 },
  { x: 5, y: 5 },
  { x: 6, y: 6 },
  { x: 10, y: 7 },
  { x: 12, y: 8 },
  { x: 15, y: 9 },
]);

console.log(lineFn(5));
// 4.92487131748987

getBrokenLineByPoints

const lineFn = Coeffs.getBrokenLineByPoints([
  { x: 4, y: 4 },
  { x: 5, y: 5 },
  { x: 6, y: 6 },
  { x: 10, y: 7 },
  { x: 12, y: 8 },
  { x: 15, y: 9 },
]);

console.log(lineFn(24));
// 12
// This function gives result in lines between your points or interpolate in
// external cases

Commands

• npm run clean - Remove lib/ directory
• npm test - Run tests with linting and coverage results.
• npm test:only - Run tests without linting or coverage.
• npm test:watch - You can even re-run tests on file changes!
• npm test:prod - Run tests with minified code.
• npm run test:examples - Test written examples on pure JS for better understanding module usage.
• npm run lint - Run ESlint with airbnb-config
• npm run cover - Get coverage report for your code.
• npm run build - Babel will transpile ES6 => ES5 and minify the code.
• npm run prepublish - Hook for npm. Do all the checks before publishing your module.

License

MIT © Den Pol