diff --git a/lib/node_modules/@stdlib/math/base/special/factorial2f/README.md b/lib/node_modules/@stdlib/math/base/special/factorial2f/README.md
new file mode 100644
index 000000000000..9966b952667e
--- /dev/null
+++ b/lib/node_modules/@stdlib/math/base/special/factorial2f/README.md
@@ -0,0 +1,216 @@
+
+
+# factorial2f
+
+> Evaluate the [double factorial][double-factorial] function as a single-precision floating-point number.
+
+
+
+The [double factorial][double-factorial] of a number `n`, denoted `n!!`, is defined as the product of all the positive integers up to `n` that have the same parity (odd or even) as `n`.
+
+Thus, for example, `5!!` is `5 * 3 * 1 = 15` and `8!!` is `8 * 6 * 4 * 2 = 384`.
+
+
+
+
+
+
+
+## Usage
+
+```javascript
+var factorial2f = require( '@stdlib/math/base/special/factorial2f' );
+```
+
+#### factorial2f( n )
+
+Evaluates the [double factorial][double-factorial] of `n` as a single-precision floating-point number.
+
+```javascript
+var v = factorial2f( 3 );
+// returns 3
+
+v = factorial2f( 4 );
+// returns 8
+
+v = factorial2f( 10 );
+// returns 3840
+```
+
+If `n > 56`, the function returns `NaN`, as larger [double factorial][double-factorial] values cannot be safely represented in [single-precision floating-point format][ieee754].
+
+```javascript
+var v = factorial2f( 57 );
+// returns Infinity
+```
+
+If not provided a nonnegative integer value, the function returns `NaN`.
+
+```javascript
+var v = factorial2f( 3.14 );
+// returns NaN
+
+v = factorial2f( -1 );
+// returns NaN
+```
+
+If provided `NaN`, the function returns `NaN`.
+
+```javascript
+var v = factorial2f( NaN );
+// returns NaN
+```
+
+
+
+
+
+
+
+## Examples
+
+
+
+```javascript
+var discreteUniform = require( '@stdlib/random/array/discrete-uniform' );
+var logEachMap = require( '@stdlib/console/log-each-map' );
+var factorial2f = require( '@stdlib/math/base/special/factorial2f' );
+
+var x = discreteUniform( 10, 0, 56, {
+ 'dtype': 'int32'
+});
+
+logEachMap( 'factorial2f(%d) = %0.1f', x, factorial2f );
+```
+
+
+
+
+
+
+
+* * *
+
+
+
+## C APIs
+
+
+
+
+
+
+
+
+
+
+
+### Usage
+
+```c
+#include "stdlib/math/base/special/factorial2f.h"
+```
+
+#### stdlib_base_factorial2f( n )
+
+Evaluates the [double factorial][double-factorial] of `n` as a single-precision floating-point number.
+
+```c
+float out = stdlib_base_factorial2f( 3 );
+// returns 3.0f
+```
+
+The function accepts the following arguments:
+
+- **n**: `[in] int32_t` input value.
+
+```c
+float stdlib_base_factorial2f( const int32_t n );
+```
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+### Examples
+
+```c
+#include "stdlib/math/base/special/factorial2f.h"
+#include
+#include
+
+int main( void ) {
+ const int32_t x[] = { 1, 10, 50, 56, 57 };
+
+ float b;
+ int i;
+ for ( i = 0; i < 5; i++ ) {
+ b = stdlib_base_factorial2f( x[ i ] );
+ printf ( "factorial2f(%d) = %f\n", x[ i ], b );
+ }
+}
+```
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+[double-factorial]: https://en.wikipedia.org/wiki/Double_factorial
+
+[ieee754]: https://en.wikipedia.org/wiki/IEEE_754-1985
+
+
+
+
+
+
+
+
diff --git a/lib/node_modules/@stdlib/math/base/special/factorial2f/benchmark/benchmark.js b/lib/node_modules/@stdlib/math/base/special/factorial2f/benchmark/benchmark.js
new file mode 100644
index 000000000000..97b43ab19652
--- /dev/null
+++ b/lib/node_modules/@stdlib/math/base/special/factorial2f/benchmark/benchmark.js
@@ -0,0 +1,54 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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 discreteUniform = require( '@stdlib/random/array/discrete-uniform' );
+var pkg = require( './../package.json' ).name;
+var factorial2f = require( './../lib' );
+
+
+// MAIN //
+
+bench( pkg, function benchmark( b ) {
+ var x;
+ var y;
+ var i;
+
+ x = discreteUniform( 100, 0, 56, {
+ 'dtype': 'int32'
+ });
+
+ b.tic();
+ for ( i = 0; i < b.iterations; i++ ) {
+ y = factorial2f( x[ i%x.length ] );
+ 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();
+});
diff --git a/lib/node_modules/@stdlib/math/base/special/factorial2f/benchmark/benchmark.native.js b/lib/node_modules/@stdlib/math/base/special/factorial2f/benchmark/benchmark.native.js
new file mode 100644
index 000000000000..697038c4d45a
--- /dev/null
+++ b/lib/node_modules/@stdlib/math/base/special/factorial2f/benchmark/benchmark.native.js
@@ -0,0 +1,63 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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-nanf' );
+var discreteUniform = require( '@stdlib/random/array/discrete-uniform' );
+var tryRequire = require( '@stdlib/utils/try-require' );
+var pkg = require( './../package.json' ).name;
+
+
+// VARIABLES //
+
+var factorial2f = tryRequire( resolve( __dirname, './../lib/native.js' ) );
+var opts = {
+ 'skip': ( factorial2f instanceof Error )
+};
+
+
+// MAIN //
+
+bench( pkg+'::native', opts, function benchmark( b ) {
+ var x;
+ var y;
+ var i;
+
+ x = discreteUniform( 100, 0, 56, {
+ 'dtype': 'int32'
+ });
+
+ b.tic();
+ for ( i = 0; i < b.iterations; i++ ) {
+ y = factorial2f( x[ i%x.length ] );
+ 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();
+});
diff --git a/lib/node_modules/@stdlib/math/base/special/factorial2f/benchmark/c/native/Makefile b/lib/node_modules/@stdlib/math/base/special/factorial2f/benchmark/c/native/Makefile
new file mode 100644
index 000000000000..a4bd7b38fd74
--- /dev/null
+++ b/lib/node_modules/@stdlib/math/base/special/factorial2f/benchmark/c/native/Makefile
@@ -0,0 +1,146 @@
+#/
+# @license Apache-2.0
+#
+# Copyright (c) 2025 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.
+#/
+
+# VARIABLES #
+
+ifndef VERBOSE
+ QUIET := @
+else
+ QUIET :=
+endif
+
+# Determine the OS ([1][1], [2][2]).
+#
+# [1]: https://en.wikipedia.org/wiki/Uname#Examples
+# [2]: http://stackoverflow.com/a/27776822/2225624
+OS ?= $(shell uname)
+ifneq (, $(findstring MINGW,$(OS)))
+ OS := WINNT
+else
+ifneq (, $(findstring MSYS,$(OS)))
+ OS := WINNT
+else
+ifneq (, $(findstring CYGWIN,$(OS)))
+ OS := WINNT
+else
+ifneq (, $(findstring Windows_NT,$(OS)))
+ OS := WINNT
+endif
+endif
+endif
+endif
+
+# Define the program used for compiling C source files:
+ifdef C_COMPILER
+ CC := $(C_COMPILER)
+else
+ CC := gcc
+endif
+
+# Define the command-line options when compiling C files:
+CFLAGS ?= \
+ -std=c99 \
+ -O3 \
+ -Wall \
+ -pedantic
+
+# Determine whether to generate position independent code ([1][1], [2][2]).
+#
+# [1]: https://gcc.gnu.org/onlinedocs/gcc/Code-Gen-Options.html#Code-Gen-Options
+# [2]: http://stackoverflow.com/questions/5311515/gcc-fpic-option
+ifeq ($(OS), WINNT)
+ fPIC ?=
+else
+ fPIC ?= -fPIC
+endif
+
+# List of includes (e.g., `-I /foo/bar -I /beep/boop/include`):
+INCLUDE ?=
+
+# List of source files:
+SOURCE_FILES ?=
+
+# List of libraries (e.g., `-lopenblas -lpthread`):
+LIBRARIES ?=
+
+# List of library paths (e.g., `-L /foo/bar -L /beep/boop`):
+LIBPATH ?=
+
+# List of C targets:
+c_targets := benchmark.out
+
+
+# RULES #
+
+#/
+# Compiles source files.
+#
+# @param {string} [C_COMPILER] - C compiler (e.g., `gcc`)
+# @param {string} [CFLAGS] - C compiler options
+# @param {(string|void)} [fPIC] - compiler flag determining whether to generate position independent code (e.g., `-fPIC`)
+# @param {string} [INCLUDE] - list of includes (e.g., `-I /foo/bar -I /beep/boop/include`)
+# @param {string} [SOURCE_FILES] - list of source files
+# @param {string} [LIBPATH] - list of library paths (e.g., `-L /foo/bar -L /beep/boop`)
+# @param {string} [LIBRARIES] - list of libraries (e.g., `-lopenblas -lpthread`)
+#
+# @example
+# make
+#
+# @example
+# make all
+#/
+all: $(c_targets)
+
+.PHONY: all
+
+#/
+# Compiles C source files.
+#
+# @private
+# @param {string} CC - C compiler (e.g., `gcc`)
+# @param {string} CFLAGS - C compiler options
+# @param {(string|void)} fPIC - compiler flag determining whether to generate position independent code (e.g., `-fPIC`)
+# @param {string} INCLUDE - list of includes (e.g., `-I /foo/bar`)
+# @param {string} SOURCE_FILES - list of source files
+# @param {string} LIBPATH - list of library paths (e.g., `-L /foo/bar`)
+# @param {string} LIBRARIES - list of libraries (e.g., `-lopenblas`)
+#/
+$(c_targets): %.out: %.c
+ $(QUIET) $(CC) $(CFLAGS) $(fPIC) $(INCLUDE) -o $@ $(SOURCE_FILES) $< $(LIBPATH) -lm $(LIBRARIES)
+
+#/
+# Runs compiled benchmarks.
+#
+# @example
+# make run
+#/
+run: $(c_targets)
+ $(QUIET) ./$<
+
+.PHONY: run
+
+#/
+# Removes generated files.
+#
+# @example
+# make clean
+#/
+clean:
+ $(QUIET) -rm -f *.o *.out
+
+.PHONY: clean
diff --git a/lib/node_modules/@stdlib/math/base/special/factorial2f/benchmark/c/native/benchmark.c b/lib/node_modules/@stdlib/math/base/special/factorial2f/benchmark/c/native/benchmark.c
new file mode 100644
index 000000000000..3dce326fbd78
--- /dev/null
+++ b/lib/node_modules/@stdlib/math/base/special/factorial2f/benchmark/c/native/benchmark.c
@@ -0,0 +1,137 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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.
+*/
+
+#include "stdlib/math/base/special/factorial2f.h"
+#include
+#include
+#include
+#include
+#include
+#include
+
+#define NAME "factorial2f"
+#define ITERATIONS 1000000
+#define REPEATS 3
+
+/**
+* Prints the TAP version.
+*/
+static void print_version( void ) {
+ printf( "TAP version 13\n" );
+}
+
+/**
+* Prints the TAP summary.
+*
+* @param total total number of tests
+* @param passing total number of passing tests
+*/
+static void print_summary( int total, int passing ) {
+ printf( "#\n" );
+ printf( "1..%d\n", total ); // TAP plan
+ printf( "# total %d\n", total );
+ printf( "# pass %d\n", passing );
+ printf( "#\n" );
+ printf( "# ok\n" );
+}
+
+/**
+* Prints benchmarks results.
+*
+* @param elapsed elapsed time in seconds
+*/
+static void print_results( double elapsed ) {
+ double rate = (double)ITERATIONS / elapsed;
+ printf( " ---\n" );
+ printf( " iterations: %d\n", ITERATIONS );
+ printf( " elapsed: %0.9f\n", elapsed );
+ printf( " rate: %0.9f\n", rate );
+ printf( " ...\n" );
+}
+
+/**
+* Returns a clock time.
+*
+* @return clock time
+*/
+static double tic( void ) {
+ struct timeval now;
+ gettimeofday( &now, NULL );
+ return (double)now.tv_sec + (double)now.tv_usec/1.0e6;
+}
+
+/**
+* Generates a random number on the interval [0,1).
+*
+* @return random number
+*/
+static float rand_float( void ) {
+ int r = rand();
+ return (float)r / ( (float)RAND_MAX + 1.0f );
+}
+
+/**
+* Runs a benchmark.
+*
+* @return elapsed time in seconds
+*/
+static double benchmark( void ) {
+ int32_t x[ 100 ];
+ double elapsed;
+ double t;
+ float y;
+ int i;
+
+ for ( i = 0; i < 100; i++ ) {
+ x[ i ] = (int32_t)( 56*rand_float() );
+ }
+
+ t = tic();
+ for ( i = 0; i < ITERATIONS; i++ ) {
+ y = stdlib_base_factorial2f( x[ i%100 ] );
+ if ( y != y ) {
+ printf( "should not return NaN\n" );
+ break;
+ }
+ }
+ elapsed = tic() - t;
+ if ( y != y ) {
+ printf( "should not return NaN\n" );
+ }
+ return elapsed;
+}
+
+/**
+* Main execution sequence.
+*/
+int main( void ) {
+ double elapsed;
+ int i;
+
+ // Use the current time to seed the random number generator:
+ srand( time( NULL ) );
+
+ print_version();
+ for ( i = 0; i < REPEATS; i++ ) {
+ printf( "# c::native::%s\n", NAME );
+ elapsed = benchmark();
+ print_results( elapsed );
+ printf( "ok %d benchmark finished\n", i+1 );
+ }
+ print_summary( REPEATS, REPEATS );
+}
diff --git a/lib/node_modules/@stdlib/math/base/special/factorial2f/binding.gyp b/lib/node_modules/@stdlib/math/base/special/factorial2f/binding.gyp
new file mode 100644
index 000000000000..68a1ca11d160
--- /dev/null
+++ b/lib/node_modules/@stdlib/math/base/special/factorial2f/binding.gyp
@@ -0,0 +1,170 @@
+# @license Apache-2.0
+#
+# Copyright (c) 2025 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.
+
+# A `.gyp` file for building a Node.js native add-on.
+#
+# [1]: https://gyp.gsrc.io/docs/InputFormatReference.md
+# [2]: https://gyp.gsrc.io/docs/UserDocumentation.md
+{
+ # List of files to include in this file:
+ 'includes': [
+ './include.gypi',
+ ],
+
+ # Define variables to be used throughout the configuration for all targets:
+ 'variables': {
+ # Target name should match the add-on export name:
+ 'addon_target_name%': 'addon',
+
+ # Set variables based on the host OS:
+ 'conditions': [
+ [
+ 'OS=="win"',
+ {
+ # Define the object file suffix:
+ 'obj': 'obj',
+ },
+ {
+ # Define the object file suffix:
+ 'obj': 'o',
+ }
+ ], # end condition (OS=="win")
+ ], # end conditions
+ }, # end variables
+
+ # Define compile targets:
+ 'targets': [
+
+ # Target to generate an add-on:
+ {
+ # The target name should match the add-on export name:
+ 'target_name': '<(addon_target_name)',
+
+ # Define dependencies:
+ 'dependencies': [],
+
+ # Define directories which contain relevant include headers:
+ 'include_dirs': [
+ # Local include directory:
+ '<@(include_dirs)',
+ ],
+
+ # List of source files:
+ 'sources': [
+ '<@(src_files)',
+ ],
+
+ # Settings which should be applied when a target's object files are used as linker input:
+ 'link_settings': {
+ # Define libraries:
+ 'libraries': [
+ '<@(libraries)',
+ ],
+
+ # Define library directories:
+ 'library_dirs': [
+ '<@(library_dirs)',
+ ],
+ },
+
+ # C/C++ compiler flags:
+ 'cflags': [
+ # Enable commonly used warning options:
+ '-Wall',
+
+ # Aggressive optimization:
+ '-O3',
+ ],
+
+ # C specific compiler flags:
+ 'cflags_c': [
+ # Specify the C standard to which a program is expected to conform:
+ '-std=c99',
+ ],
+
+ # C++ specific compiler flags:
+ 'cflags_cpp': [
+ # Specify the C++ standard to which a program is expected to conform:
+ '-std=c++11',
+ ],
+
+ # Linker flags:
+ 'ldflags': [],
+
+ # Apply conditions based on the host OS:
+ 'conditions': [
+ [
+ 'OS=="mac"',
+ {
+ # Linker flags:
+ 'ldflags': [
+ '-undefined dynamic_lookup',
+ '-Wl,-no-pie',
+ '-Wl,-search_paths_first',
+ ],
+ },
+ ], # end condition (OS=="mac")
+ [
+ 'OS!="win"',
+ {
+ # C/C++ flags:
+ 'cflags': [
+ # Generate platform-independent code:
+ '-fPIC',
+ ],
+ },
+ ], # end condition (OS!="win")
+ ], # end conditions
+ }, # end target <(addon_target_name)
+
+ # Target to copy a generated add-on to a standard location:
+ {
+ 'target_name': 'copy_addon',
+
+ # Declare that the output of this target is not linked:
+ 'type': 'none',
+
+ # Define dependencies:
+ 'dependencies': [
+ # Require that the add-on be generated before building this target:
+ '<(addon_target_name)',
+ ],
+
+ # Define a list of actions:
+ 'actions': [
+ {
+ 'action_name': 'copy_addon',
+ 'message': 'Copying addon...',
+
+ # Explicitly list the inputs in the command-line invocation below:
+ 'inputs': [],
+
+ # Declare the expected outputs:
+ 'outputs': [
+ '<(addon_output_dir)/<(addon_target_name).node',
+ ],
+
+ # Define the command-line invocation:
+ 'action': [
+ 'cp',
+ '<(PRODUCT_DIR)/<(addon_target_name).node',
+ '<(addon_output_dir)/<(addon_target_name).node',
+ ],
+ },
+ ], # end actions
+ }, # end target copy_addon
+ ], # end targets
+}
diff --git a/lib/node_modules/@stdlib/math/base/special/factorial2f/docs/repl.txt b/lib/node_modules/@stdlib/math/base/special/factorial2f/docs/repl.txt
new file mode 100644
index 000000000000..8f362fe7b25b
--- /dev/null
+++ b/lib/node_modules/@stdlib/math/base/special/factorial2f/docs/repl.txt
@@ -0,0 +1,39 @@
+
+{{alias}}( n )
+ Evaluates the double factorial of `n` as a single-precision floating-point
+ number.
+
+ If `n` is greater than `56`, the function returns `NaN`, as larger double
+ factorial values cannot be accurately represented due to limitations of
+ single-precision floating-point format.
+
+ If not provided a nonnegative integer value, the function returns `NaN`.
+
+ If provided `NaN`, the function returns `NaN`.
+
+ Parameters
+ ----------
+ n: number
+ Input value.
+
+ Returns
+ -------
+ y: number
+ Double factorial.
+
+ Examples
+ --------
+ > var y = {{alias}}( 3 )
+ 3
+ > y = {{alias}}( 4 )
+ 8
+ > y = {{alias}}( 57 )
+ Infinity
+ > y = {{alias}}( -10 )
+ NaN
+ > y = {{alias}}( NaN )
+ NaN
+
+ See Also
+ --------
+
diff --git a/lib/node_modules/@stdlib/math/base/special/factorial2f/docs/types/index.d.ts b/lib/node_modules/@stdlib/math/base/special/factorial2f/docs/types/index.d.ts
new file mode 100644
index 000000000000..b886be047623
--- /dev/null
+++ b/lib/node_modules/@stdlib/math/base/special/factorial2f/docs/types/index.d.ts
@@ -0,0 +1,58 @@
+/*
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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.
+*/
+
+// TypeScript Version: 4.1
+
+/**
+* Evaluates the double factorial of `n` as a single-precision floating-point number.
+*
+* ## Notes
+*
+* - If `n` is greater than `56`, the function returns `NaN`, as larger double factorial values cannot be accurately represented due to limitations of single-precision floating-point format.
+* - If not provided a nonnegative integer value, the function returns `NaN`.
+*
+* @param n - input value
+* @returns double factorial
+*
+* @example
+* var v = factorial2f( 3 );
+* // returns 3
+*
+* @example
+* var v = factorial2f( 4 );
+* // returns 8
+*
+* @example
+* var v = factorial2f( 57 );
+* // returns Infinity
+*
+* @example
+* var v = factorial2f( -10 );
+* // returns NaN
+*
+* @example
+* var v = factorial2f( NaN );
+* // returns NaN
+*/
+declare function factorial2f( n: number ): number;
+
+
+// EXPORTS //
+
+export = factorial2f;
+
diff --git a/lib/node_modules/@stdlib/math/base/special/factorial2f/docs/types/test.ts b/lib/node_modules/@stdlib/math/base/special/factorial2f/docs/types/test.ts
new file mode 100644
index 000000000000..377778944f99
--- /dev/null
+++ b/lib/node_modules/@stdlib/math/base/special/factorial2f/docs/types/test.ts
@@ -0,0 +1,44 @@
+/*
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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.
+*/
+
+import factorial2f = require( './index' );
+
+
+// TESTS //
+
+// The function returns a number...
+{
+ factorial2f( 2 ); // $ExpectType number
+}
+
+// The compiler throws an error if the function is provided a value other than a number...
+{
+ factorial2f( true ); // $ExpectError
+ factorial2f( false ); // $ExpectError
+ factorial2f( null ); // $ExpectError
+ factorial2f( undefined ); // $ExpectError
+ factorial2f( '5' ); // $ExpectError
+ factorial2f( [] ); // $ExpectError
+ factorial2f( {} ); // $ExpectError
+ factorial2f( ( x: number ): number => x ); // $ExpectError
+}
+
+// The compiler throws an error if the function is provided insufficient arguments...
+{
+ factorial2f(); // $ExpectError
+}
diff --git a/lib/node_modules/@stdlib/math/base/special/factorial2f/examples/c/Makefile b/lib/node_modules/@stdlib/math/base/special/factorial2f/examples/c/Makefile
new file mode 100644
index 000000000000..25ced822f96a
--- /dev/null
+++ b/lib/node_modules/@stdlib/math/base/special/factorial2f/examples/c/Makefile
@@ -0,0 +1,146 @@
+#/
+# @license Apache-2.0
+#
+# Copyright (c) 2025 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.
+#/
+
+# VARIABLES #
+
+ifndef VERBOSE
+ QUIET := @
+else
+ QUIET :=
+endif
+
+# Determine the OS ([1][1], [2][2]).
+#
+# [1]: https://en.wikipedia.org/wiki/Uname#Examples
+# [2]: http://stackoverflow.com/a/27776822/2225624
+OS ?= $(shell uname)
+ifneq (, $(findstring MINGW,$(OS)))
+ OS := WINNT
+else
+ifneq (, $(findstring MSYS,$(OS)))
+ OS := WINNT
+else
+ifneq (, $(findstring CYGWIN,$(OS)))
+ OS := WINNT
+else
+ifneq (, $(findstring Windows_NT,$(OS)))
+ OS := WINNT
+endif
+endif
+endif
+endif
+
+# Define the program used for compiling C source files:
+ifdef C_COMPILER
+ CC := $(C_COMPILER)
+else
+ CC := gcc
+endif
+
+# Define the command-line options when compiling C files:
+CFLAGS ?= \
+ -std=c99 \
+ -O3 \
+ -Wall \
+ -pedantic
+
+# Determine whether to generate position independent code ([1][1], [2][2]).
+#
+# [1]: https://gcc.gnu.org/onlinedocs/gcc/Code-Gen-Options.html#Code-Gen-Options
+# [2]: http://stackoverflow.com/questions/5311515/gcc-fpic-option
+ifeq ($(OS), WINNT)
+ fPIC ?=
+else
+ fPIC ?= -fPIC
+endif
+
+# List of includes (e.g., `-I /foo/bar -I /beep/boop/include`):
+INCLUDE ?=
+
+# List of source files:
+SOURCE_FILES ?=
+
+# List of libraries (e.g., `-lopenblas -lpthread`):
+LIBRARIES ?=
+
+# List of library paths (e.g., `-L /foo/bar -L /beep/boop`):
+LIBPATH ?=
+
+# List of C targets:
+c_targets := example.out
+
+
+# RULES #
+
+#/
+# Compiles source files.
+#
+# @param {string} [C_COMPILER] - C compiler (e.g., `gcc`)
+# @param {string} [CFLAGS] - C compiler options
+# @param {(string|void)} [fPIC] - compiler flag determining whether to generate position independent code (e.g., `-fPIC`)
+# @param {string} [INCLUDE] - list of includes (e.g., `-I /foo/bar -I /beep/boop/include`)
+# @param {string} [SOURCE_FILES] - list of source files
+# @param {string} [LIBPATH] - list of library paths (e.g., `-L /foo/bar -L /beep/boop`)
+# @param {string} [LIBRARIES] - list of libraries (e.g., `-lopenblas -lpthread`)
+#
+# @example
+# make
+#
+# @example
+# make all
+#/
+all: $(c_targets)
+
+.PHONY: all
+
+#/
+# Compiles C source files.
+#
+# @private
+# @param {string} CC - C compiler (e.g., `gcc`)
+# @param {string} CFLAGS - C compiler options
+# @param {(string|void)} fPIC - compiler flag determining whether to generate position independent code (e.g., `-fPIC`)
+# @param {string} INCLUDE - list of includes (e.g., `-I /foo/bar`)
+# @param {string} SOURCE_FILES - list of source files
+# @param {string} LIBPATH - list of library paths (e.g., `-L /foo/bar`)
+# @param {string} LIBRARIES - list of libraries (e.g., `-lopenblas`)
+#/
+$(c_targets): %.out: %.c
+ $(QUIET) $(CC) $(CFLAGS) $(fPIC) $(INCLUDE) -o $@ $(SOURCE_FILES) $< $(LIBPATH) -lm $(LIBRARIES)
+
+#/
+# Runs compiled examples.
+#
+# @example
+# make run
+#/
+run: $(c_targets)
+ $(QUIET) ./$<
+
+.PHONY: run
+
+#/
+# Removes generated files.
+#
+# @example
+# make clean
+#/
+clean:
+ $(QUIET) -rm -f *.o *.out
+
+.PHONY: clean
diff --git a/lib/node_modules/@stdlib/math/base/special/factorial2f/examples/c/example.c b/lib/node_modules/@stdlib/math/base/special/factorial2f/examples/c/example.c
new file mode 100644
index 000000000000..91ee56b05395
--- /dev/null
+++ b/lib/node_modules/@stdlib/math/base/special/factorial2f/examples/c/example.c
@@ -0,0 +1,32 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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.
+*/
+
+#include "stdlib/math/base/special/factorial2f.h"
+#include
+#include
+
+int main( void ) {
+ const int32_t x[] = { 1, 10, 50, 56, 57 };
+
+ float b;
+ int i;
+ for ( i = 0; i < 5; i++ ) {
+ b = stdlib_base_factorial2f( x[ i ] );
+ printf ( "factorial2f(%d) = %f\n", x[ i ], b );
+ }
+}
diff --git a/lib/node_modules/@stdlib/math/base/special/factorial2f/examples/index.js b/lib/node_modules/@stdlib/math/base/special/factorial2f/examples/index.js
new file mode 100644
index 000000000000..3417202ea467
--- /dev/null
+++ b/lib/node_modules/@stdlib/math/base/special/factorial2f/examples/index.js
@@ -0,0 +1,29 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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';
+
+var discreteUniform = require( '@stdlib/random/array/discrete-uniform' );
+var logEachMap = require( '@stdlib/console/log-each-map' );
+var factorial2f = require( './../lib' );
+
+var x = discreteUniform( 10, 0, 56, {
+ 'dtype': 'int32'
+});
+
+logEachMap( 'factorial2f(%d) = %0.1f', x, factorial2f );
diff --git a/lib/node_modules/@stdlib/math/base/special/factorial2f/include.gypi b/lib/node_modules/@stdlib/math/base/special/factorial2f/include.gypi
new file mode 100644
index 000000000000..ecfaf82a3279
--- /dev/null
+++ b/lib/node_modules/@stdlib/math/base/special/factorial2f/include.gypi
@@ -0,0 +1,53 @@
+# @license Apache-2.0
+#
+# Copyright (c) 2025 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.
+
+# A GYP include file for building a Node.js native add-on.
+#
+# Main documentation:
+#
+# [1]: https://gyp.gsrc.io/docs/InputFormatReference.md
+# [2]: https://gyp.gsrc.io/docs/UserDocumentation.md
+{
+ # Define variables to be used throughout the configuration for all targets:
+ 'variables': {
+ # Source directory:
+ 'src_dir': './src',
+
+ # Include directories:
+ 'include_dirs': [
+ '
+
+/*
+* If C++, prevent name mangling so that the compiler emits a binary file having undecorated names, thus mirroring the behavior of a C compiler.
+*/
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+* Evaluates the double factorial of `n` as a single-precision floating-point number.
+*/
+float stdlib_base_factorial2f( const int32_t n );
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // !STDLIB_MATH_BASE_SPECIAL_FACTORIAL2F_H
diff --git a/lib/node_modules/@stdlib/math/base/special/factorial2f/lib/index.js b/lib/node_modules/@stdlib/math/base/special/factorial2f/lib/index.js
new file mode 100644
index 000000000000..749f4c17b0cf
--- /dev/null
+++ b/lib/node_modules/@stdlib/math/base/special/factorial2f/lib/index.js
@@ -0,0 +1,52 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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';
+
+/**
+* Evaluate the double factorial function as a single-precision floating-point number.
+*
+* @module @stdlib/math/base/special/factorial2f
+*
+* @example
+* var factorial2f = require( '@stdlib/math/base/special/factorial2f' );
+*
+* var v = factorial2f( 3 );
+* // returns 3
+*
+* v = factorial2f( 4 );
+* // returns 8
+*
+* v = factorial2f( 57 );
+* // returns Infinity
+*
+* v = factorial2f( -10 );
+* // returns NaN
+*
+* v = factorial( NaN );
+* // returns NaN
+*/
+
+// MODULES //
+
+var main = require( './main.js' );
+
+
+// EXPORTS //
+
+module.exports = main;
diff --git a/lib/node_modules/@stdlib/math/base/special/factorial2f/lib/main.js b/lib/node_modules/@stdlib/math/base/special/factorial2f/lib/main.js
new file mode 100644
index 000000000000..df43a587c86e
--- /dev/null
+++ b/lib/node_modules/@stdlib/math/base/special/factorial2f/lib/main.js
@@ -0,0 +1,93 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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 isnanf = require( '@stdlib/math/base/assert/is-nanf' );
+var isIntegerf = require( '@stdlib/math/base/assert/is-integerf' );
+var isEvenf = require( '@stdlib/math/base/assert/is-evenf' );
+var float64ToFloat32 = require( '@stdlib/number/float64/base/to-float32' );
+var PINF = require( '@stdlib/constants/float32/pinf' );
+var FLOAT32_MAX_NTH_DOUBLE_FACTORIAL = require( '@stdlib/constants/float32/max-nth-double-factorial' ); // eslint-disable-line id-length
+
+
+// MAIN //
+
+/**
+* Evaluates the double factorial of `n` as a single-precision floating-point number.
+*
+* @param {number} n - input value
+* @returns {(NonNegativeInteger|number)} double factorial
+*
+* @example
+* var v = factorial2f( 3 );
+* // returns 3
+*
+* @example
+* var v = factorial2f( 4 );
+* // returns 8
+*
+* @example
+* var v = factorial2f( 57 );
+* // returns Infinity
+*
+* @example
+* var v = factorial2f( -10 );
+* // returns NaN
+*
+* @example
+* var v = factorial2f( NaN );
+* // returns NaN
+*/
+function factorial2f( n ) {
+ var last;
+ var out;
+ var v;
+ var i;
+
+ if ( isnanf( n ) ) {
+ return NaN;
+ }
+ if ( n > FLOAT32_MAX_NTH_DOUBLE_FACTORIAL ) {
+ return PINF;
+ }
+ if ( n < 0 || isIntegerf( n ) === false ) {
+ return NaN;
+ }
+ v = n|0; // asm type annotation
+ if ( v === 0|0 || v === 1|0 ) {
+ return 1|0; // asm type annotation
+ }
+ if ( isEvenf( v ) ) {
+ last = 2|0; // asm type annotation
+ } else {
+ last = 3|0; // asm type annotation
+ }
+ out = float64ToFloat32( 1 );
+ for ( i = v|0; i >= last; i -= 2|0 ) {
+ out = float64ToFloat32( out * i );
+ }
+ return out;
+}
+
+
+// EXPORTS //
+
+module.exports = factorial2f;
diff --git a/lib/node_modules/@stdlib/math/base/special/factorial2f/lib/native.js b/lib/node_modules/@stdlib/math/base/special/factorial2f/lib/native.js
new file mode 100644
index 000000000000..6c24b01a46bf
--- /dev/null
+++ b/lib/node_modules/@stdlib/math/base/special/factorial2f/lib/native.js
@@ -0,0 +1,58 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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 addon = require( './../src/addon.node' );
+
+
+// MAIN //
+
+/**
+* Evaluates the double factorial of `n` as a single-precision floating-point number.
+*
+* @private
+* @param {number} n - input value
+* @returns {(NonNegativeInteger|number)} double factorial
+*
+* @example
+* var v = factorial2f( 3 );
+* // returns 3
+*
+* @example
+* var v = factorial2f( 4 );
+* // returns 8
+*
+* @example
+* var v = factorial2f( 57 );
+* // returns Infinity
+*
+* @example
+* var v = factorial2f( -10 );
+* // returns NaN
+*/
+function factorial2f( n ) {
+ return addon( n );
+}
+
+
+// EXPORTS //
+
+module.exports = factorial2f;
diff --git a/lib/node_modules/@stdlib/math/base/special/factorial2f/manifest.json b/lib/node_modules/@stdlib/math/base/special/factorial2f/manifest.json
new file mode 100644
index 000000000000..e908a7d99888
--- /dev/null
+++ b/lib/node_modules/@stdlib/math/base/special/factorial2f/manifest.json
@@ -0,0 +1,78 @@
+{
+ "options": {
+ "task": "build"
+ },
+ "fields": [
+ {
+ "field": "src",
+ "resolve": true,
+ "relative": true
+ },
+ {
+ "field": "include",
+ "resolve": true,
+ "relative": true
+ },
+ {
+ "field": "libraries",
+ "resolve": false,
+ "relative": false
+ },
+ {
+ "field": "libpath",
+ "resolve": true,
+ "relative": false
+ }
+ ],
+ "confs": [
+ {
+ "task": "build",
+ "src": [
+ "./src/main.c"
+ ],
+ "include": [
+ "./include"
+ ],
+ "libraries": [],
+ "libpath": [],
+ "dependencies": [
+ "@stdlib/math/base/napi/unary",
+ "@stdlib/math/base/assert/int32-is-even",
+ "@stdlib/constants/float32/pinf",
+ "@stdlib/constants/float32/max-nth-double-factorial"
+ ]
+ },
+ {
+ "task": "benchmark",
+ "src": [
+ "./src/main.c"
+ ],
+ "include": [
+ "./include"
+ ],
+ "libraries": [],
+ "libpath": [],
+ "dependencies": [
+ "@stdlib/math/base/assert/int32-is-even",
+ "@stdlib/constants/float32/pinf",
+ "@stdlib/constants/float32/max-nth-double-factorial"
+ ]
+ },
+ {
+ "task": "examples",
+ "src": [
+ "./src/main.c"
+ ],
+ "include": [
+ "./include"
+ ],
+ "libraries": [],
+ "libpath": [],
+ "dependencies": [
+ "@stdlib/math/base/assert/int32-is-even",
+ "@stdlib/constants/float32/pinf",
+ "@stdlib/constants/float32/max-nth-double-factorial"
+ ]
+ }
+ ]
+}
diff --git a/lib/node_modules/@stdlib/math/base/special/factorial2f/package.json b/lib/node_modules/@stdlib/math/base/special/factorial2f/package.json
new file mode 100644
index 000000000000..d0bb10defedb
--- /dev/null
+++ b/lib/node_modules/@stdlib/math/base/special/factorial2f/package.json
@@ -0,0 +1,71 @@
+{
+ "name": "@stdlib/math/base/special/factorial2f",
+ "version": "0.0.0",
+ "description": "Evaluate the double factorial function as a single-precision floating-point number.",
+ "license": "Apache-2.0",
+ "author": {
+ "name": "The Stdlib Authors",
+ "url": "https://github.com/stdlib-js/stdlib/graphs/contributors"
+ },
+ "contributors": [
+ {
+ "name": "The Stdlib Authors",
+ "url": "https://github.com/stdlib-js/stdlib/graphs/contributors"
+ }
+ ],
+ "main": "./lib",
+ "gypfile": true,
+ "directories": {
+ "benchmark": "./benchmark",
+ "doc": "./docs",
+ "example": "./examples",
+ "include": "./include",
+ "lib": "./lib",
+ "src": "./src",
+ "test": "./test"
+ },
+ "types": "./docs/types",
+ "scripts": {},
+ "homepage": "https://github.com/stdlib-js/stdlib",
+ "repository": {
+ "type": "git",
+ "url": "git://github.com/stdlib-js/stdlib.git"
+ },
+ "bugs": {
+ "url": "https://github.com/stdlib-js/stdlib/issues"
+ },
+ "dependencies": {},
+ "devDependencies": {},
+ "engines": {
+ "node": ">=0.10.0",
+ "npm": ">2.7.0"
+ },
+ "os": [
+ "aix",
+ "darwin",
+ "freebsd",
+ "linux",
+ "macos",
+ "openbsd",
+ "sunos",
+ "win32",
+ "windows"
+ ],
+ "keywords": [
+ "stdlib",
+ "stdmath",
+ "mathematics",
+ "math",
+ "special functions",
+ "special",
+ "function",
+ "factorial",
+ "fact",
+ "dfact",
+ "factorialf",
+ "factorial2f",
+ "combinatorics",
+ "double",
+ "number"
+ ]
+}
diff --git a/lib/node_modules/@stdlib/math/base/special/factorial2f/src/Makefile b/lib/node_modules/@stdlib/math/base/special/factorial2f/src/Makefile
new file mode 100644
index 000000000000..7733b6180cb4
--- /dev/null
+++ b/lib/node_modules/@stdlib/math/base/special/factorial2f/src/Makefile
@@ -0,0 +1,70 @@
+#/
+# @license Apache-2.0
+#
+# Copyright (c) 2025 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.
+#/
+
+# VARIABLES #
+
+ifndef VERBOSE
+ QUIET := @
+else
+ QUIET :=
+endif
+
+# Determine the OS ([1][1], [2][2]).
+#
+# [1]: https://en.wikipedia.org/wiki/Uname#Examples
+# [2]: http://stackoverflow.com/a/27776822/2225624
+OS ?= $(shell uname)
+ifneq (, $(findstring MINGW,$(OS)))
+ OS := WINNT
+else
+ifneq (, $(findstring MSYS,$(OS)))
+ OS := WINNT
+else
+ifneq (, $(findstring CYGWIN,$(OS)))
+ OS := WINNT
+else
+ifneq (, $(findstring Windows_NT,$(OS)))
+ OS := WINNT
+endif
+endif
+endif
+endif
+
+
+# RULES #
+
+#/
+# Removes generated files for building an add-on.
+#
+# @example
+# make clean-addon
+#/
+clean-addon:
+ $(QUIET) -rm -f *.o *.node
+
+.PHONY: clean-addon
+
+#/
+# Removes generated files.
+#
+# @example
+# make clean
+#/
+clean: clean-addon
+
+.PHONY: clean
diff --git a/lib/node_modules/@stdlib/math/base/special/factorial2f/src/addon.c b/lib/node_modules/@stdlib/math/base/special/factorial2f/src/addon.c
new file mode 100644
index 000000000000..b2b2f522d3c3
--- /dev/null
+++ b/lib/node_modules/@stdlib/math/base/special/factorial2f/src/addon.c
@@ -0,0 +1,22 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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.
+*/
+
+#include "stdlib/math/base/special/factorial2f.h"
+#include "stdlib/math/base/napi/unary.h"
+
+STDLIB_MATH_BASE_NAPI_MODULE_I_F( stdlib_base_factorial2f )
diff --git a/lib/node_modules/@stdlib/math/base/special/factorial2f/src/main.c b/lib/node_modules/@stdlib/math/base/special/factorial2f/src/main.c
new file mode 100644
index 000000000000..21420f00973e
--- /dev/null
+++ b/lib/node_modules/@stdlib/math/base/special/factorial2f/src/main.c
@@ -0,0 +1,59 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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.
+*/
+
+#include "stdlib/math/base/special/factorial2f.h"
+#include "stdlib/math/base/assert/int32_is_even.h"
+#include "stdlib/constants/float32/pinf.h"
+#include "stdlib/constants/float32/max_nth_double_factorial.h"
+#include
+
+/**
+* Evaluates the double factorial of `n` as a single-precision floating-point number.
+*
+* @param x input value
+* @return double factorial
+*
+* @example
+* float v = stdlib_base_factorial2f( 3 );
+* // returns 3.0f
+*/
+float stdlib_base_factorial2f( const int32_t n ) {
+ int32_t last;
+ int32_t i;
+ float out;
+
+ if ( n > STDLIB_CONSTANT_FLOAT32_MAX_NTH_DOUBLE_FACTORIAL ) {
+ return STDLIB_CONSTANT_FLOAT32_PINF;
+ }
+ if ( n < 0 ) {
+ return 0.0f / 0.0f; // NaN
+ }
+ if ( n == 0 || n == 1 ) {
+ return 1.0f;
+ }
+ if ( stdlib_base_int32_is_even( n ) ) {
+ last = 2;
+ } else {
+ last = 3;
+ }
+ out = 1.0f;
+ for ( i = n; i >= last; i -= 2 ) {
+ out *= i;
+ }
+ return out;
+}
diff --git a/lib/node_modules/@stdlib/math/base/special/factorial2f/test/fixtures/python/data.json b/lib/node_modules/@stdlib/math/base/special/factorial2f/test/fixtures/python/data.json
new file mode 100644
index 000000000000..516310e2be8e
--- /dev/null
+++ b/lib/node_modules/@stdlib/math/base/special/factorial2f/test/fixtures/python/data.json
@@ -0,0 +1 @@
+{"x": [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56], "expected": [1.0, 2.0, 3.0, 8.0, 15.0, 48.0, 105.0, 384.0, 945.0, 3840.0, 10395.0, 46080.0, 135135.0, 645120.0, 2027025.0, 10321920.0, 34459424.0, 185794560.0, 654729088.0, 3715891200.0, 13749310464.0, 81749606400.0, 316234137600.0, 1961990553600.0, 7905853571072.0, 51011754393600.0, 213458045894656.0, 1428329089466368.0, 6190283213504512.0, 4.284987509991014e+16, 1.9189877800802714e+17, 1.3711960031971246e+18, 6.332659760164241e+18, 4.662066081016735e+19, 2.21643089956481e+20, 1.6783438067582108e+21, 8.200794275613239e+21, 6.377706859746168e+22, 3.198309818154659e+23, 2.5510826718408733e+24, 1.3113070938981246e+25, 1.0714546875855216e+26, 5.638620319294495e+26, 4.7144007360567597e+27, 2.537379221158848e+28, 2.1686244035186486e+29, 1.1925682221387423e+30, 1.0409396532426603e+31, 5.843584250700905e+31, 5.204698387105884e+32, 2.980227992035978e+33, 2.7064431922435605e+34, 1.5795207738820664e+35, 1.4614792891492016e+36, 8.687364216737284e+36, 8.184284399530709e+37]}
diff --git a/lib/node_modules/@stdlib/math/base/special/factorial2f/test/fixtures/python/runner.py b/lib/node_modules/@stdlib/math/base/special/factorial2f/test/fixtures/python/runner.py
new file mode 100644
index 000000000000..60be06e89fa9
--- /dev/null
+++ b/lib/node_modules/@stdlib/math/base/special/factorial2f/test/fixtures/python/runner.py
@@ -0,0 +1,71 @@
+#!/usr/bin/env python
+#
+# @license Apache-2.0
+#
+# Copyright (c) 2025 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.
+
+"""Generate fixtures."""
+
+import os
+import json
+import numpy as np
+from scipy.special import factorial2
+
+# Get the file path:
+FILE = os.path.realpath(__file__)
+
+# Extract the directory in which this file resides:
+DIR = os.path.dirname(FILE)
+
+
+def gen(x, name):
+ """Generate fixture data and write to file.
+
+ # Arguments
+
+ * `x`: domain
+ * `name::str`: output filename
+
+ # Examples
+
+ ``` python
+ python> x = linspace(-1000, 1000, 2001)
+ python> gen(x, './data.json')
+ ```
+ """
+ y = factorial2(x, exact=False).astype(np.float32)
+
+ # Store data to be written to file as a dictionary:
+ data = {
+ "x": x.tolist(),
+ "expected": y.tolist()
+ }
+
+ # Based on the script directory, create an output filepath:
+ filepath = os.path.join(DIR, name)
+
+ # Write the data to the output filepath as JSON:
+ with open(filepath, "w", encoding="utf-8") as outfile:
+ json.dump(data, outfile)
+
+
+def main():
+ """Generate fixture data."""
+ x = np.arange(1, 57, dtype=np.int32)
+ gen(x, "data.json")
+
+
+if __name__ == "__main__":
+ main()
diff --git a/lib/node_modules/@stdlib/math/base/special/factorial2f/test/test.js b/lib/node_modules/@stdlib/math/base/special/factorial2f/test/test.js
new file mode 100644
index 000000000000..7a771934da50
--- /dev/null
+++ b/lib/node_modules/@stdlib/math/base/special/factorial2f/test/test.js
@@ -0,0 +1,111 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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 tape = require( 'tape' );
+var isnanf = require( '@stdlib/math/base/assert/is-nanf' );
+var absf = require( '@stdlib/math/base/special/absf' );
+var incrspace = require( '@stdlib/array/base/incrspace' );
+var PINF = require( '@stdlib/constants/float32/pinf' );
+var NINF = require( '@stdlib/constants/float32/ninf' );
+var EPS = require( '@stdlib/constants/float32/eps' );
+var factorial2f = require( './../lib' );
+
+
+// FIXTURES //
+
+var data = require( './fixtures/python/data.json' );
+
+
+// TESTS //
+
+tape( 'main export is a function', function test( t ) {
+ t.ok( true, __filename );
+ t.strictEqual( typeof factorial2f, 'function', 'main export is a function' );
+ t.end();
+});
+
+tape( 'if provided a negative integer, the function returns `NaN`', function test( t ) {
+ var values;
+ var v;
+ var i;
+
+ values = incrspace( -1.0, -1000.0, -25.0 );
+ for ( i = 0; i < values.length; i++ ) {
+ v = factorial2f( values[ i ] );
+ t.strictEqual( isnanf( v ), true, 'returns expected value' );
+ }
+ t.end();
+});
+
+tape( 'if provided negative infinity, the function returns `NaN`', function test( t ) {
+ var v = factorial2f( NINF );
+ t.strictEqual( isnanf( v ), true, 'returns expected value' );
+ t.end();
+});
+
+tape( 'if provided positive infinity, the function returns `+infinity`', function test( t ) {
+ var v = factorial2f( PINF );
+ t.strictEqual( v, PINF, 'returns expected value' );
+ t.end();
+});
+
+tape( 'if provided `NaN`, the function returns `NaN`', function test( t ) {
+ var v = factorial2f( NaN );
+ t.strictEqual( isnanf( v ), true, 'returns expected value' );
+ t.end();
+});
+
+tape( 'the function evaluates the double factorial', function test( t ) {
+ var expected;
+ var delta;
+ var tol;
+ var x;
+ var v;
+ var i;
+
+ x = data.x;
+ expected = data.expected;
+
+ for ( i = 0; i < x.length; i++ ) {
+ v = factorial2f( x[ i ] );
+ if ( v === expected[ i ] ) {
+ t.strictEqual( v, expected[ i ], 'returns expected value' );
+ } else {
+ delta = absf( v - expected[i] );
+
+ // NOTE: We use approximate equality because expected values from SciPy are computed using gamma function approximations instead of iterative single-precision computation.
+ tol = 2.4 * EPS * absf( expected[i] );
+ t.ok( delta <= tol, 'within tolerance. x: '+x[i]+'. v: '+v+'. e: '+expected[i]+'. Δ: '+delta+'. tol: '+tol+'.' );
+ }
+ }
+ t.end();
+});
+
+tape( 'if provided data greater than `56`, the function returns positive infinity', function test( t ) {
+ var i;
+ var v;
+ for ( i = 57; i < 100; i++ ) {
+ v = factorial2f( i );
+ t.strictEqual( v, PINF, 'returns expected value' );
+ }
+ t.end();
+});
diff --git a/lib/node_modules/@stdlib/math/base/special/factorial2f/test/test.native.js b/lib/node_modules/@stdlib/math/base/special/factorial2f/test/test.native.js
new file mode 100644
index 000000000000..cf6cd8bdc4c5
--- /dev/null
+++ b/lib/node_modules/@stdlib/math/base/special/factorial2f/test/test.native.js
@@ -0,0 +1,101 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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 tape = require( 'tape' );
+var isnanf = require( '@stdlib/math/base/assert/is-nanf' );
+var absf = require( '@stdlib/math/base/special/absf' );
+var incrspace = require( '@stdlib/array/base/incrspace' );
+var PINF = require( '@stdlib/constants/float32/pinf' );
+var EPS = require( '@stdlib/constants/float32/eps' );
+var tryRequire = require( '@stdlib/utils/try-require' );
+
+
+// FIXTURES //
+
+var data = require( './fixtures/python/data.json' );
+
+
+// VARIABLES //
+
+var factorial2f = tryRequire( resolve( __dirname, './../lib/native.js' ) );
+var opts = {
+ 'skip': ( factorial2f instanceof Error )
+};
+
+
+// TESTS //
+
+tape( 'main export is a function', opts, function test( t ) {
+ t.ok( true, __filename );
+ t.strictEqual( typeof factorial2f, 'function', 'main export is a function' );
+ t.end();
+});
+
+tape( 'if provided a negative integer, the function returns `NaN`', opts, function test( t ) {
+ var values;
+ var v;
+ var i;
+
+ values = incrspace( -1.0, -1000.0, -25.0 );
+ for ( i = 0; i < values.length; i++ ) {
+ v = factorial2f( values[ i ] );
+ t.strictEqual( isnanf( v ), true, 'returns expected value' );
+ }
+ t.end();
+});
+
+tape( 'the function evaluates the double factorial', opts, function test( t ) {
+ var expected;
+ var delta;
+ var tol;
+ var x;
+ var v;
+ var i;
+
+ x = data.x;
+ expected = data.expected;
+
+ for ( i = 0; i < x.length; i++ ) {
+ v = factorial2f( x[ i ] );
+ if ( v === expected[ i ] ) {
+ t.strictEqual( v, expected[ i ], 'returns expected value' );
+ } else {
+ delta = absf( v - expected[i] );
+
+ // NOTE: We use approximate equality because expected values from SciPy are computed using gamma function approximations instead of iterative single-precision computation.
+ tol = 2.4 * EPS * absf( expected[i] );
+ t.ok( delta <= tol, 'within tolerance. x: '+x[i]+'. v: '+v+'. e: '+expected[i]+'. Δ: '+delta+'. tol: '+tol+'.' );
+ }
+ }
+ t.end();
+});
+
+tape( 'if provided data greater than `56`, the function returns positive infinity', opts, function test( t ) {
+ var i;
+ var v;
+ for ( i = 57; i < 100; i++ ) {
+ v = factorial2f( i );
+ t.strictEqual( v, PINF, 'returns expected value' );
+ }
+ t.end();
+});