stdlib-js
<summary>
About stdlib...
</summary>
We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.
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factorialln
[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url]
Natural logarithm of the [factorial function][factorial-function].
n. Thus, factorialln( n ) is generally preferred to ln( n! ).
bash
npm install @stdlib/math-base-special-factorialln
javascript
var factorialln = require( '@stdlib/math-base-special-factorialln' );
#### factorialln( x )
Evaluates the natural logarithm of the [factorial function][factorial-function]. For input values other than negative integers, the function returns ln( x! ) = ln( Γ(x+1) ), where Γ is the [Gamma][gamma-function] function. For negative integers, the function returns NaN.
javascript
var v = factorialln( 3.0 );
// returns ~1.792
v = factorialln( 2.4 );
// returns ~1.092
v = factorialln( -1.0 );
// returns NaN
v = factorialln( -1.5 );
// returns ~1.266
If provided NaN, the function returns NaN.
javascript
var v = factorialln( NaN );
// returns NaN
javascript
var incrspace = require( '@stdlib/array-base-incrspace' );
var factorialln = require( '@stdlib/math-base-special-factorialln' );
var x = incrspace( -10.0, 50.0, 0.5 );
var i;
for ( i = 0; i < x.length; i++ ) {
console.log( 'x: %d, f(x): %d', x[ i ], factorialln( x[ i ] ) );
}
@stdlib/math-base/special/factorial][@stdlib/math/base/special/factorial]: evaluate a factorial.
