math-gamma

Gamma Function

Gamma function.

The gamma function extends the factorial function to real and complex numbers. If n is a positive integer,

Generalized to all complex numbers z, except for non-positive integers, the gamma function can be expressed as an infinite product

where γ ≈ 0.577216 is the Euler–Mascheroni constant.

Installation

$ npm install math-gamma

Usage

var gamma = require( 'math-gamma' );

gamma( x )

Evaluates the gamma function.

var val = gamma( 4 );
// returns 3! = 6
 
val = gamma( -3/2 );
// returns ~2.363
 
val = gamma( -1/2 );
// returns ~-3.545
 
val = gamma( 1/2 );
// returns ~1.772

Examples

var linspace = require( 'compute-linspace' );
var gamma = require( 'math-gamma' );
 
var x = linspace( -10, 10, 100 );
var v;
var i;
 
for ( i = 0; i < x.length; i++ ) {
    v = gamma( x[ i ] );
    console.log( 'x: %d, f(x): %d', x[ i ], v );
}

To run the example code from the top-level application directory,

$ node ./examples/index.js

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Tests

Unit

This repository uses tape for unit tests. To run the tests, execute the following command in the top-level application directory:

$ make test

All new feature development should have corresponding unit tests to validate correct functionality.

Test Coverage

This repository uses Istanbul as its code coverage tool. To generate a test coverage report, execute the following command in the top-level application directory:

$ make test-cov

Istanbul creates a ./reports/coverage directory. To access an HTML version of the report,

$ make view-cov

Browser Support

This repository uses Testling for browser testing. To run the tests in a (headless) local web browser, execute the following command in the top-level application directory:

$ make test-browsers

To view the tests in a local web browser,

$ make view-browser-tests

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License

MIT license.

Copyright

Copyright © 2016. The Compute.io Authors.