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feat(factorialf):implementation for math/base/special/factorialf
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‎lib/node_modules/@stdlib/math/base/special/factorialf/README.md‎

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<!--
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@license Apache-2.0
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Copyright (c) 2026 The Stdlib Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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# factorialf
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> [Factorial][factorial-function] function of a single-precision floating-point number.
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<section class="intro">
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The [factorial][factorial-function] function may be defined as the product
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```math
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n! = \prod_{k=1}^n k
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```
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or according to the recurrence relation
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```math
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n! = \begin{cases}1 & \textrm{if } n = 0,\\(n-1)! \times n & \textrm{if } n > 1\end{cases}
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```
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Following the convention for an [empty product][empty-product], in all definitions,
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```math
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0! = 1
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```
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The [Gamma][@stdlib/math/base/special/gamma] function extends the [factorial][factorial-function] function for non-integer values.
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```math
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n! = \Gamma(n+1)
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```
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The [factorial][factorial-function] of a **negative** integer is not defined.
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</section>
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<!-- /.intro -->
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<section class="usage">
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## Usage
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```javascript
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var factorialf = require( '@stdlib/math/base/special/factorialf' );
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```
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#### factorialf( x )
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Evaluates the [factorial][factorial-function] function of a single-precision floating-point number.
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```javascript
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var v = factorialf( 3.0 );
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// returns 6.0
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v = factorialf( -1.5 );
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// returns ~-3.545
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v = factorialf( -0.5 );
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// returns ~1.772
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v = factorialf( 0.5 );
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// returns ~0.886
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v = factorialf( -10.0 );
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// returns NaN
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v = factorialf( 34.0 );
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// returns ~2.952e38
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v = factorialf( 35.0 );
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// returns Infinity
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v = factorialf( NaN );
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// returns NaN
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```
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</section>
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<!-- /.usage -->
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<section class="examples">
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## Examples
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<!-- eslint no-undef: "error" -->
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```javascript
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var incrspace = require( '@stdlib/array/base/incrspace' );
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var factorialf = require( '@stdlib/math/base/special/factorialf' );
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var x = incrspace( -10.0, 50.0, 1.0 );
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var i;
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for ( i = 0; i < x.length; i++ ) {
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console.log( 'x: %d, f(x): %d', x[ i ], factorialf( x[ i ] ) );
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}
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```
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</section>
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<!-- /.examples -->
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<!-- C interface documentation. -->
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* * *
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<section class="c">
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## C APIs
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<section class="intro">
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</section>
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<!-- /.intro -->
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<!-- C usage documentation. -->
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<section class="usage">
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### Usage
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```c
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#include "stdlib/math/base/special/factorialf.h"
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```
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#### stdlib_base_factorialf( x )
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Evaluates the [factorial][factorial-function] function of a single-precision floating-point number.
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```c
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float out = stdlib_base_factorialf( 3.0f );
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// returns 6.0f
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out = stdlib_base_factorialf( -1.5f );
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// returns ~-3.545f
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```
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The function accepts the following arguments:
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- **x**: `[in] float` input value.
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```c
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float stdlib_base_factorialf( const float x );
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```
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</section>
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<!-- /.usage -->
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<section class="notes">
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</section>
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<!-- /.notes -->
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<section class="examples">
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### Examples
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```c
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#include "stdlib/math/base/special/factorialf.h"
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#include <stdio.h>
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int main( void ) {
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const float x[] = { 2.0f, 3.0f, 5.0f, 8.0f };
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float y;
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int i;
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for ( i = 0; i < 4; i++ ) {
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y = stdlib_base_factorialf( x[ i ] );
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printf( "factorialf(%f) = %f\n", x[ i ], y );
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}
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}
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```
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</section>
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<!-- /.examples -->
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</section>
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<!-- /.c -->
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<section class="related">
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* * *
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## See Also
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- <span class="package-name">[`@stdlib/math/base/special/factorial`][@stdlib/math/base/special/factorial]</span><span class="delimiter">: </span><span class="description">evaluate the factorial function.</span>
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- <span class="package-name">[`@stdlib/math/base/special/factoriallnf`][@stdlib/math/base/special/factoriallnf]</span><span class="delimiter">: </span><span class="description">evaluate the natural logarithm of the factorial function of a single-precision floating-point number.</span>
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</section>
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<!-- /.related -->
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<section class="links">
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[@stdlib/math/base/special/gamma]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/math/base/special/gamma
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[factorial-function]: https://en.wikipedia.org/wiki/Factorial
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[empty-product]: https://en.wikipedia.org/wiki/Empty_product
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<!-- <related-links> -->
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[@stdlib/math/base/special/factorial]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/math/base/special/factorial
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[@stdlib/math/base/special/factoriallnf]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/math/base/special/factoriallnf
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<!-- </related-links> -->
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</section>
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<!-- /.links -->

‎lib/node_modules/@stdlib/math/base/special/factorialf/benchmark/benchmark.js‎

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/**
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* @license Apache-2.0
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*
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* Copyright (c) 2026 The Stdlib Authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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'use strict';
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// MODULES //
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var bench = require( '@stdlib/bench' );
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var isnanf = require( '@stdlib/math/base/assert/is-nanf' );
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var pkg = require( './../package.json' ).name;
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var factorialf = require( './../lib' );
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// MAIN //
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bench( pkg+'::integers', function benchmark( b ) {
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var y;
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var i;
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b.tic();
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for ( i = 0; i < b.iterations; i++ ) {
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y = factorialf( i%35 );
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if ( isnanf( y ) ) {
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b.fail( 'should not return NaN' );
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}
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}
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b.toc();
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if ( isnanf( y ) ) {
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b.fail( 'should not return NaN' );
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}
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b.pass( 'benchmark finished' );
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b.end();
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});
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bench( pkg+'::decimals', function benchmark( b ) {
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var y;
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var i;
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b.tic();
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for ( i = 0; i < b.iterations; i++ ) {
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y = factorialf( (i%35)*0.68163 );
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if ( isnanf( y ) ) {
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b.fail( 'should not return NaN' );
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}
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}
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b.toc();
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if ( isnanf( y ) ) {
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b.fail( 'should not return NaN' );
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}
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b.pass( 'benchmark finished' );
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b.end();
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});

‎lib/node_modules/@stdlib/math/base/special/factorialf/benchmark/benchmark.native.js‎

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/**
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* @license Apache-2.0
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*
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* Copyright (c) 2026 The Stdlib Authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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'use strict';
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// MODULES //
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var resolve = require( 'path' ).resolve;
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var bench = require( '@stdlib/bench' );
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var isnanf = require( '@stdlib/math/base/assert/is-nan' );
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var tryRequire = require( '@stdlib/utils/try-require' );
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var pkg = require( './../package.json' ).name;
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// VARIABLES //
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var factorialf = tryRequire( resolve( __dirname, './../lib/native.js' ) );
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var opts = {
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'skip': ( factorialf instanceof Error )
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};
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// MAIN //
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bench( pkg+'::native,integers', opts, function benchmark( b ) {
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var y;
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var i;
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b.tic();
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for ( i = 0; i < b.iterations; i++ ) {
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y = factorialf( i % 171 );
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if ( isnanf( y ) ) {
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b.fail( 'should not return NaN' );
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}
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}
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b.toc();
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if ( isnanf( y ) ) {
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b.fail( 'should not return NaN' );
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}
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b.pass( 'benchmark finished' );
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b.end();
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});
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bench( pkg+'::native,decimals', opts, function benchmark( b ) {
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var y;
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var i;
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b.tic();
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for ( i = 0; i < b.iterations; i++ ) {
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y = factorialf( ( i % 171 ) * 0.68163 );
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if ( isnanf( y ) ) {
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b.fail( 'should not return NaN' );
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}
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}
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b.toc();
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if ( isnanf( y ) ) {
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b.fail( 'should not return NaN' );
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}
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b.pass( 'benchmark finished' );
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b.end();
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});

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