CocoRoboDesktop/pdf1.js/node_modules/cephes/build/readme-header.md

node-cephes

This is a WebAssembly packaging of the cephes library. The cephes library contains C implementations of most special functions, distributions, and other hard-to-implement mathematical functions.

Note that there are a few cephes functions that are not exposed here, as some of them are quite hard to make consumable in JavaScript using WebAssembly. Feel free to send a pull request if you need one of them.

Install

npm install cephes

If you are looking on GitHub, you will notice some files are missing. These are statically built from the cephes library. See the CONTRIBUTING.md file, for how to build them.

Usage

Cephes is a WebAssembly module but is very small and fast to compile, as it doesn't depend on any runtime libraries. In Node.js it is therefore compiled synchronously and all you need to do is require the module.

const cephes = require('cephes'); // Node.js

In the browser, it is, for good practice, compiled asynchronously. You must therefore wait for the .compiled promise to be resolved.

const cephes = require('cephes'); // Browser
await cephes.compiled;

Note that the .compiled promise is also available in Node.js, but it is simply a dummy promise that resolves immediately.

The JavaScript interface

There are three variations of functions to be aware of:

1. Plain numeric function

These don't require anything special.

const value = cephes.zeta(2, 1);

2. Functions that return more than one value

In C, these functions return a primary value and then return extra value using pointer arguments. In JavaScript this is implemented as a function that returns an array of length 2. The first element is the primary returned value, the second is an object of the extra returned values.

const [value, {ai, aip, bi, bip}] = cephes.airy(-1);

3. Functions that consumes an array

Some functions consumes an array of values, these must be TypedArrays of the appropriate type. These functions will typically also require a variation of .length value as a parameter, like you would do in C. Be aware, that in some cases it may not be exactly the .length of the TypedArray, but may be one less or one more. Check the specific function documentation to be sure.

const arrayInput = new Float64Array([2.2, 3.3, 4.4]);
const value = ephes.polevl(1.1, arrayInput, arrayInput.length - 1);