node-simplemath.js

SimpleMath.js

SimpleMath.js is an extensive math library for JavaScript and Node.js. It features a flexible expression parser with support for symbolic computation, comes with a large set of built-in functions and constants, and offers an integrated solution to work with different data types like numbers, big numbers, complex numbers, fractions, units, and matrices. Powerful and easy to use.

Features

• Supports numbers, big numbers, complex numbers, fractions, units, strings, arrays, and matrices.
• Is compatible with JavaScript's built-in Math library.
• Contains a flexible expression parser.
• Does symbolic computation.
• Comes with a large set of built-in functions and constants.
• Can be used as a command line application as well.
• Runs on any JavaScript engine.
• Is easily extensible.
• Open source.

Usage

Math.js can be used in both node.js and in the browser.

Install simplemath.js using npm

$   npm install node-simplemath.js

Note that when using simplemath.js in a TypeScript project, you will have to install type definition files too: npm install @types/node-simplemath.js.

import {
  atan2, chain, derivative, e, evaluate, log, pi, pow, round, sqrt
} from 'node-simplemath.js'

// functions and constants
round(e, 3)                    // 2.718
atan2(3, -3) / pi              // 0.75
log(10000, 10)                 // 4
sqrt(-4)                       // 2i
pow([[-1, 2], [3, 1]], 2)      // [[7, 0], [0, 7]]
derivative('x^2 + x', 'x')     // 2 * x + 1

// expressions
evaluate('12 / (2.3 + 0.7)')   // 4
evaluate('12.7 cm to inch')    // 5 inch
evaluate('sin(45 deg) ^ 2')    // 0.5
evaluate('9 / 3 + 2i')         // 3 + 2i
evaluate('det([-1, 2; 3, 1])') // -7

// chaining
chain(3)
    .add(4)
    .multiply(2)
    .done()  // 14

Code

The code of node-simplemath.js is written in ES modules, and requires all files to have a real, relative path, meaning the files must have a *.js extension. Please configure adding file extensions on auto import in your IDE.

Architecture

What mathjs tries to achieve is to offer an environment where you can do calculations with mixed data types, like multiplying a regular number with a Complex number or a BigNumber, and work with all of those in matrices. Mathjs also allows to add a new data type, like say BigInt, with little effort.

The solution that mathjs uses has two main ingredients:

• Typed functions. All functions are created using typed function. This makes it easier to (dynamically) create and extend a single function with new data types, automatically do type conversions on function inputs, etc. So, if you create function multiply for two numbers, you can extend it with support for multiplying two BigInts. If you define a conversion from BigInt to number, the typed-function will automatically allow you to multiply a BigInt with a number.

• Dependency injection. When we have a function multiply with support for BigInt, thanks to the dependency injection, other functions using multiply under the hood, like prod, will automatically support BigInt too. This also works the other way around: if you don't need the heavyweight multiply (which supports BigNumbers, matrices, etc), and you just need a plain and simple number support, you can use a lightweight implementation of multiply just for numbers, and inject that in prod and other functions.

At the lowest level, mathjs has immutable factory functions which create immutable functions. The core function math.create(...) creates a new instance having functions created from all passed factory functions. A mathjs instance is a collection of created functions. It contains a function like math.import to allow extending the instance with new functions, which can then be used in the expression parser.