@stdlib/math-base-special-factorial
v0.3.2TypeScript
Evaluate a factorial.
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Published by The Stdlib Authors
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factorial
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> [Factorial][factorial-function] function.
The [factorial][factorial-function] function may be defined as the product
or according to the recurrence relation
Following the convention for an [empty product][empty-product], in all definitions,
The [Gamma][@stdlib/math/base/special/gamma] function extends the [factorial][factorial-function] function for non-integer values.
The [factorial][factorial-function] of a negative integer is not defined.
Installation
``bash`
npm install @stdlib/math-base-special-factorial
Usage
`javascript`
var factorial = require( '@stdlib/math-base-special-factorial' );
#### factorial( x )
Evaluates the [factorial][factorial-function] function.
`javascript
var v = factorial( 3.0 );
// returns 6.0
v = factorial( -1.5 );
// returns ~-3.545
v = factorial( -0.5 );
// returns ~1.772
v = factorial( 0.5 );
// returns ~0.886
v = factorial( -10.0 );
// returns NaN
v = factorial( 171.0 );
// returns Infinity
v = factorial( NaN );
// returns NaN
`
Examples
`javascript
var incrspace = require( '@stdlib/array-base-incrspace' );
var factorial = require( '@stdlib/math-base-special-factorial' );
var x = incrspace( -10.0, 100.0, 1.0 );
var i;
for ( i = 0; i < x.length; i++ ) {
console.log( 'x: %d, f(x): %d', x[ i ], factorial( x[ i ] ) );
}
`
*
C APIs
$3
`c`
#include "stdlib/math/base/special/factorial.h"
#### stdlib_base_factorial( x )
Evaluates the [factorial][factorial-function] function.
`c
double out = stdlib_base_factorial( 3.0 );
// returns 6.0
out = stdlib_base_factorial( -1.5 );
// returns ~-3.545
`
The function accepts the following arguments:
- x: [in] double input value.
`c`
double stdlib_base_factorial( const double x );
$3
`c
#include "stdlib/math/base/special/factorial.h"
#include
int main( void ) {
const double x[] = { 2.0, 3.0, 5.0, 8.0 };
double y;
int i;
for ( i = 0; i < 4; i++ ) {
y = stdlib_base_factorial( x[ i ] );
printf( "factorial(%lf) = %lf\n", x[ i ], y );
}
}
`
*
See Also
- [@stdlib/math-base/special/factorialln][@stdlib/math/base/special/factorialln]: evaluate the natural logarithm of the factorial function.
*
Notice
This package is part of [stdlib][stdlib], a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.
For more information on the project, filing bug reports and feature requests, and guidance on how to develop [stdlib][stdlib], see the main project [repository][stdlib].
#### Community
[![Chat][chat-image]][chat-url]
---
License
See [LICENSE][stdlib-license].
Copyright
Copyright © 2016-2026. The Stdlib [Authors][stdlib-authors].
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[npm-url]: https://npmjs.org/package/@stdlib/math-base-special-factorial
[test-image]: https://github.com/stdlib-js/math-base-special-factorial/actions/workflows/test.yml/badge.svg?branch=v0.3.2
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[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/math-base-special-factorial/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/math-base-special-factorial?branch=main
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[chat-url]: https://stdlib.zulipchat.com
[stdlib]: https://github.com/stdlib-js/stdlib
[stdlib-authors]: https://github.com/stdlib-js/stdlib/graphs/contributors
[umd]: https://github.com/umdjs/umd
[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules
[deno-url]: https://github.com/stdlib-js/math-base-special-factorial/tree/deno
[deno-readme]: https://github.com/stdlib-js/math-base-special-factorial/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/math-base-special-factorial/tree/umd
[umd-readme]: https://github.com/stdlib-js/math-base-special-factorial/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/math-base-special-factorial/tree/esm
[esm-readme]: https://github.com/stdlib-js/math-base-special-factorial/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/math-base-special-factorial/blob/main/branches.md
[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/math-base-special-factorial/main/LICENSE
[@stdlib/math/base/special/gamma]: https://www.npmjs.com/package/@stdlib/math-base-special-gamma
[factorial-function]: https://en.wikipedia.org/wiki/Factorial
[empty-product]: https://en.wikipedia.org/wiki/Empty_product
[@stdlib/math/base/special/factorialln]: https://www.npmjs.com/package/@stdlib/math-base-special-factorialln