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  • License MIT

Linear conversion class for linear-converter

Package Exports

  • linear-conversion

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (linear-conversion) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

linear-conversion

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Linear conversion class for linear-converter

Install

npm i linear-conversion

Basic usage

var temp = require('linear-presets-temperature');
var LinearConversion = require('linear-conversion')(require('floating-adapter'));

var celsiusToFahrenheit = new LinearConversion(temp.celsiusToFahrenheit);

celsiusToFahrenheit.convert(25); // => 77

See CodePen example for a quick interactive intro.

Conversion inversion

var fahrenheitToCelsius = celsiusToFahrenheit.invert();

fahrenheitToCelsius.convert(77); // => 25

Conversion composition

var celsiusToKelvin = new LinearConversion(temp.celsiusToKelvin);
var kelvinToFahrenheit = celsiusToKelvin.invert().compose([celsiusToFahrenheit]);

kelvinToFahrenheit.convert(293.15); // => 68

Custom conversions

Custom conversions are easily achieved by passing an array with 2 scales, each of those an array with 2 values. For example, [[0, 1], [0, 2]] means that 0 and 1 in the first scale map to 0 and 2 in the second scale respectively; in short, it multiplies by 2. Any linear conversion can be described that way:

// f(x) = ax + b
(new LinearConversion([[0, 1], [b, a+b]])).convert(x); // => ax + b
(new LinearConversion([[1/a, -b/a], [b+1, 0]])).convert(x); // => ax + b

For an arbitrary f(x) = ax + b, any [[x1, x2], [f(x1), f(x2)]] is a valid preset.

More examples:

// degrees to radians
(new LinearConversion([[0, 180], [0, Math.PI]])).convert(240); // => 4 * Math.PI / 3

// f(x) = 3x
(new LinearConversion([[0, 1/3], [0, 1]])).convert(5); // => 15

// f(x) = -2x - 46
(new LinearConversion([[0, 1], [-46, -48]])).convert(-23); // => 0

Coefficients

Creating presets from a given function is trivial; to find the function from a given preset, two methods are provided: getCoefficientA and getCoefficientB.

// f(x) = 2x + 1
var doublePlus1 = new LinearConversion([[0, 1], [1, 3]]);

doublePlus1.getCoefficientA(); // => 2
doublePlus1.getCoefficientB(); // => 1

// f(x) = ax + b
var timesAPlusB = new LinearConversion([[x1, x2], [f(x1), f(x2)]]);

timesAPlusB.getCoefficientA(); // => a
timesAPlusB.getCoefficientB(); // => b

Arbitrary precision

Arbitrary precision support is provided via linear-arbitrary-precision. See all available adapters.

var doublePlusPoint1 = new LinearConversion([[0, 0.1], [0.1, 0.3]]);

// without arbitrary precision adapters
doublePlusPoint1.getCoefficientA(); // => 1.9999999999999998

// with arbitrary precision adapters
doublePlusPoint1.getCoefficientA(); // => 2

See CodePen example.

See more