feat: add math/base/special/factorialf

lib/node_modules/@stdlib/math/base/special/factorialf/README.md

@@ -0,0 +1,234 @@
+<!--
+
+@license Apache-2.0
+
+Copyright (c) 2026 The Stdlib Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+
+-->
+
+# factorialf
+
+> Evaluate the [Factorial][factorial-function] function of a single-precision floating-point number.
+
+<section class="intro">
+
+The [factorial][factorial-function] function may be defined as the product
+
+```math
+n! = \prod_{k=1}^n k
+```
+
+or according to the recurrence relation
+
+```math
+n! = \begin{cases}1 & \textrm{if } n = 0,\\(n-1)! \times n & \textrm{if } n > 1\end{cases}
+```
+
+Following the convention for an [empty product][empty-product], in all definitions,
+
+```math
+0! = 1
+```
+
+The [Gamma][@stdlib/math/base/special/gamma] function extends the [factorial][factorial-function] function for non-integer values.
+
+```math
+n! = \Gamma(n+1)
+```
+
+The [factorial][factorial-function] of a **negative** integer is not defined.
+
+</section>
+
+<!-- /.intro -->
+
+<section class="usage">
+
+## Usage
+
+```javascript
+var factorialf = require( '@stdlib/math/base/special/factorialf' );
+```
+
+#### factorialf( x )
+
+Evaluates the [factorial][factorial-function] function of a single-precision floating-point number.
+
+```javascript
+var v = factorialf( 3.0 );
+// returns 6.0
+
+v = factorialf( -1.5 );
+// returns ~-3.545
+
+v = factorialf( -0.5 );
+// returns ~1.772
+
+v = factorialf( 0.5 );
+// returns ~0.886
+
+v = factorialf( -10.0 );
+// returns NaN
+
+v = factorialf( 34.0 );
+// returns ~2.952e38
+
+v = factorialf( 35.0 );
+// returns Infinity
+
+v = factorialf( NaN );
+// returns NaN
+```
+
+</section>
+
+<!-- /.usage -->
+
+<section class="examples">
+
+## Examples
+
+<!-- eslint no-undef: "error" -->
+
+```javascript
+var incrspace = require( '@stdlib/array/base/incrspace' );
+var factorialf = require( '@stdlib/math/base/special/factorialf' );
+
+var x = incrspace( -10.0, 50.0, 1.0 );
+
+var i;
+for ( i = 0; i < x.length; i++ ) {
+    console.log( 'x: %d, f(x): %d', x[ i ], factorialf( x[ i ] ) );
+}
+```
+
+</section>
+
+<!-- /.examples -->
+
+<!-- C interface documentation. -->
+
+* * *
+
+<section class="c">
+
+## C APIs
+
+<section class="intro">
+
+</section>
+
+<!-- /.intro -->
+
+<!-- C usage documentation. -->
+
+<section class="usage">
+
+### Usage
+
+```c
+#include "stdlib/math/base/special/factorialf.h"
+```
+
+#### stdlib_base_factorialf( x )
+
+Evaluates the [factorial][factorial-function] function of a single-precision floating-point number.
+
+```c
+float out = stdlib_base_factorialf( 3.0f );
+// returns 6.0f
+
+out = stdlib_base_factorialf( -1.5f );
+// returns ~-3.545f
+```
+
+The function accepts the following arguments:
+
+-   **x**: `[in] float` input value.
+
+```c
+float stdlib_base_factorialf( const float x );
+```
+
+</section>
+
+<!-- /.usage -->
+
+<section class="notes">
+
+</section>
+
+<!-- /.notes -->
+
+<section class="examples">
+
+### Examples
+
+```c
+#include "stdlib/math/base/special/factorialf.h"
+#include <stdio.h>
+
+int main( void ) {
+    const float x[] = { 2.0f, 3.0f, 5.0f, 8.0f };
+
+    float y;
+    int i;
+    for ( i = 0; i < 4; i++ ) {
+        y = stdlib_base_factorialf( x[ i ] );
+        printf( "factorialf(%f) = %f\n", x[ i ], y );
+    }
+}
+```
+
+</section>
+
+<!-- /.examples -->
+
+</section>
+
+<!-- /.c -->
+
+<section class="related">
+
+* * *
+
+## See Also
+
+-   <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>
+-   <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>
+
+</section>
+
+<!-- /.related -->
+
+<section class="links">
+
+[@stdlib/math/base/special/gamma]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/math/base/special/gamma
+
+[factorial-function]: https://en.wikipedia.org/wiki/Factorial
+
+[empty-product]: https://en.wikipedia.org/wiki/Empty_product
+
+<!-- <related-links> -->
+
+[@stdlib/math/base/special/factorial]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/math/base/special/factorial
+
+[@stdlib/math/base/special/factoriallnf]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/math/base/special/factoriallnf
+
+<!-- </related-links> -->
+
+</section>
+
+<!-- /.links -->

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

@@ -0,0 +1,67 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2026 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+*    http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+'use strict';
+
+// MODULES //
+
+var bench = require( '@stdlib/bench' );
+var isnanf = require( '@stdlib/math/base/assert/is-nanf' );
+var pkg = require( './../package.json' ).name;
+var factorialf = require( './../lib' );
+
+
+// MAIN //
+
+bench( pkg+'::integers', function benchmark( b ) {
+	var y;
+	var i;
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		y = factorialf( i%35 );
+		if ( isnanf( y ) ) {
+			b.fail( 'should not return NaN' );
+		}
+	}
+	b.toc();
+	if ( isnanf( y ) ) {
+		b.fail( 'should not return NaN' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});
+
+bench( pkg+'::decimals', function benchmark( b ) {
+	var y;
+	var i;
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		y = factorialf( (i%35)*0.68163 );
+		if ( isnanf( y ) ) {
+			b.fail( 'should not return NaN' );
+		}
+	}
+	b.toc();
+	if ( isnanf( y ) ) {
+		b.fail( 'should not return NaN' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});

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

@@ -0,0 +1,76 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2026 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+*    http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+'use strict';
+
+// MODULES //
+
+var resolve = require( 'path' ).resolve;
+var bench = require( '@stdlib/bench' );
+var isnanf = require( '@stdlib/math/base/assert/is-nan' );
+var tryRequire = require( '@stdlib/utils/try-require' );
+var pkg = require( './../package.json' ).name;
+
+
+// VARIABLES //
+
+var factorialf = tryRequire( resolve( __dirname, './../lib/native.js' ) );
+var opts = {
+	'skip': ( factorialf instanceof Error )
+};
+
+
+// MAIN //
+
+bench( pkg+'::native,integers', opts, function benchmark( b ) {
+	var y;
+	var i;
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		y = factorialf( i % 171 );
+		if ( isnanf( y ) ) {
+			b.fail( 'should not return NaN' );
+		}
+	}
+	b.toc();
+	if ( isnanf( y ) ) {
+		b.fail( 'should not return NaN' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});
+
+bench( pkg+'::native,decimals', opts, function benchmark( b ) {
+	var y;
+	var i;
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		y = factorialf( ( i % 171 ) * 0.68163 );
+		if ( isnanf( y ) ) {
+			b.fail( 'should not return NaN' );
+		}
+	}
+	b.toc();
+	if ( isnanf( y ) ) {
+		b.fail( 'should not return NaN' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});