diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/README.md b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/README.md
new file mode 100644
index 000000000000..14ce4879906d
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/README.md
@@ -0,0 +1,259 @@
+<!--
+
+@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.
+
+-->
+
+# Probability Density Function
+
+> [Half-normal][halfnormal-distribution] distribution probability density function (PDF).
+
+<section class="intro">
+
+The [probability density function][pdf] (PDF) for a [half-normal][halfnormal-distribution] random variable is
+
+<!-- <equation class="equation" label="eq:halfnormal_pdf" align="center" raw="f(x;\sigma)=\frac{\sqrt{2}}{\sigma\sqrt{\pi}}\, e^{-\frac{x^2}{2 \sigma^2}}" alt="Probability density function (PDF) for a half-normal distribution."> -->
+
+```math
+f(x;\sigma)=\frac{\sqrt{2}}{\sigma\sqrt{\pi}}\, e^{-\frac{x^2}{2 \sigma^2}}
+```
+
+<!-- <div class="equation" align="center" data-raw-text="f(x;\sigma)=\frac{\sqrt{2}}{\sigma\sqrt{\pi}}\, e^{-\frac{x^2}{2 \sigma^2}}" data-equation="eq:halfnormal_pdf">
+    <img src="https://cdn.jsdelivr.net/gh/stdlib-js/stdlib@51534079fef45e990850102147e8945fb023d1d0/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/docs/img/equation_halfnormal_pdf.svg" alt="Probability density function (PDF) for a half-normal distribution.">
+    <br>
+</div> -->
+
+<!-- </equation> -->
+
+where `σ` is the scale parameter.
+
+</section>
+
+<!-- /.intro -->
+
+<section class="usage">
+
+## Usage
+
+```javascript
+var pdf = require( '@stdlib/stats/base/dists/halfnormal/pdf' );
+```
+
+#### pdf( x, sigma )
+
+Evaluates the [probability density function][pdf] (PDF) for a [half-normal][halfnormal-distribution] distribution with parameter `sigma` (scale parameter).
+
+```javascript
+var y = pdf( 2.0, 1.0 );
+// returns ~0.108
+
+y = pdf( 1.0, 4.0 );
+// returns ~0.193
+```
+
+If provided `NaN` as any argument, the function returns `NaN`.
+
+```javascript
+var y = pdf( NaN, 1.0 );
+// returns NaN
+
+y = pdf( 0.0, NaN );
+// returns NaN
+```
+
+If provided `sigma <= 0`, the function returns `NaN`.
+
+```javascript
+var y = pdf( 2.0, -1.0 );
+// returns NaN
+
+y = pdf( 2.0, 0.0 );
+// returns NaN
+```
+
+If provided a negative value for `x`, the function returns `0.0`.
+
+```javascript
+var y = pdf( -1.0, 1.0 );
+// returns 0.0
+```
+
+#### pdf.factory( sigma )
+
+Returns a function for evaluating the [probability density function][pdf] (PDF) of a [half-normal][halfnormal-distribution] distribution with parameter `sigma` (scale parameter).
+
+```javascript
+var mypdf = pdf.factory( 2.0 );
+
+var y = mypdf( 3.0 );
+// returns ~0.130
+
+y = mypdf( 1.0 );
+// returns ~0.352
+```
+
+</section>
+
+<!-- /.usage -->
+
+<section class="examples">
+
+## Examples
+
+<!-- eslint no-undef: "error" -->
+
+```javascript
+var uniform = require( '@stdlib/random/array/uniform' );
+var logEachMap = require( '@stdlib/console/log-each-map' );
+var pdf = require( '@stdlib/stats/base/dists/halfnormal/pdf' );
+
+var opts = {
+    'dtype': 'float64'
+};
+var sigma = uniform( 10, 0.0, 20.0, opts );
+var x = uniform( 10, 0.0, 10.0, opts );
+
+logEachMap( 'x: %0.4f, σ: %0.4f, f(x;σ): %0.4f', x, sigma, pdf );
+```
+
+</section>
+
+<!-- /.examples -->
+
+<!-- C interface documentation. -->
+
+* * *
+
+<section class="c">
+
+## C APIs
+
+<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->
+
+<section class="intro">
+
+</section>
+
+<!-- /.intro -->
+
+<!-- C usage documentation. -->
+
+<section class="usage">
+
+### Usage
+
+```c
+#include "stdlib/stats/base/dists/halfnormal/pdf.h"
+```
+
+#### stdlib_base_dists_halfnormal_pdf( x, sigma )
+
+Evaluates the [probability density function][pdf] (PDF) for a [half-normal][halfnormal-distribution] distribution with parameter `sigma` (scale parameter).
+
+```c
+double y = stdlib_base_dists_halfnormal_pdf( 2.0, 1.0 );
+// returns ~0.108
+```
+
+The function accepts the following arguments:
+
+-   **x**: `[in] double` input value.
+-   **sigma**: `[in] double` scale parameter.
+
+```c
+double stdlib_base_dists_halfnormal_pdf( const double x, const double sigma );
+```
+
+</section>
+
+<!-- /.usage -->
+
+<!-- C API usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="notes">
+
+</section>
+
+<!-- /.notes -->
+
+<!-- C API usage examples. -->
+
+<section class="examples">
+
+### Examples
+
+```c
+#include "stdlib/stats/base/dists/halfnormal/pdf.h"
+#include "stdlib/constants/float64/eps.h"
+#include <stdlib.h>
+#include <stdio.h>
+
+static double random_uniform( const double min, const double max ) {
+    double v = (double)rand() / ( (double)RAND_MAX + 1.0 );
+    return min + ( v*(max-min) );
+}
+
+int main( void ) {
+    double sigma;
+    double x;
+    double y;
+    int i;
+
+    for ( i = 0; i < 10; i++ ) {
+        x = random_uniform( 0.0, 10.0 );
+        sigma = random_uniform( STDLIB_CONSTANT_FLOAT64_EPS, 20.0 );
+        y = stdlib_base_dists_halfnormal_pdf( x, sigma );
+        printf( "x: %lf, σ: %lf, f(x;σ): %lf\n", x, sigma, y );
+    }
+}
+```
+
+</section>
+
+<!-- /.examples -->
+
+</section>
+
+<!-- /.c -->
+
+<!-- Section to include cited references. If references are included, add a horizontal rule *before* the section. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="references">
+
+</section>
+
+<!-- /.references -->
+
+<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->
+
+<section class="related">
+
+</section>
+
+<!-- /.related -->
+
+<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="links">
+
+[pdf]: https://en.wikipedia.org/wiki/Probability_density_function
+
+[halfnormal-distribution]: https://en.wikipedia.org/wiki/Half-normal_distribution
+
+</section>
+
+<!-- /.links -->
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/benchmark/benchmark.js b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/benchmark/benchmark.js
new file mode 100644
index 000000000000..575780e5aa87
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/benchmark/benchmark.js
@@ -0,0 +1,90 @@
+/**
+* @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 uniform = require( '@stdlib/random/array/uniform' );
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+var EPS = require( '@stdlib/constants/float64/eps' );
+var pkg = require( './../package.json' ).name;
+var pdf = require( './../lib' );
+
+
+// MAIN //
+
+bench( pkg, function benchmark( b ) {
+	var sigma;
+	var opts;
+	var x;
+	var y;
+	var i;
+
+	opts = {
+		'dtype': 'float64'
+	};
+	x = uniform( 100, 0.0, 10.0, opts );
+	sigma = uniform( 100, EPS, 10.0, opts );
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		y = pdf( x[ i % x.length ], sigma[ i % sigma.length ] );
+		if ( isnan( y ) ) {
+			b.fail( 'should not return NaN' );
+		}
+	}
+	b.toc();
+	if ( isnan( y ) ) {
+		b.fail( 'should not return NaN' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});
+
+bench( pkg+':factory', function benchmark( b ) {
+	var pdfFunc;
+	var sigma;
+	var opts;
+	var x;
+	var y;
+	var i;
+
+	opts = {
+		'dtype': 'float64'
+	};
+	x = uniform( 100, 0.0, 10.0, opts );
+	sigma = 2.0;
+
+	pdfFunc = pdf.factory( sigma );
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		y = pdfFunc( x[ i % x.length ] );
+		if ( isnan( y ) ) {
+			b.fail( 'should not return NaN' );
+		}
+	}
+	b.toc();
+	if ( isnan( y ) ) {
+		b.fail( 'should not return NaN' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/benchmark/benchmark.native.js b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/benchmark/benchmark.native.js
new file mode 100644
index 000000000000..63a10263c7e7
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/benchmark/benchmark.native.js
@@ -0,0 +1,68 @@
+/**
+* @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 EPS = require( '@stdlib/constants/float64/eps' );
+var uniform = require( '@stdlib/random/array/uniform' );
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+var tryRequire = require( '@stdlib/utils/try-require' );
+var pkg = require( './../package.json' ).name;
+
+
+// VARIABLES //
+
+var pdf = tryRequire( resolve( __dirname, './../lib/native.js' ) );
+var opts = {
+	'skip': ( pdf instanceof Error )
+};
+
+
+// MAIN //
+
+bench( pkg+'::native', opts, function benchmark( b ) {
+	var sigma;
+	var opts;
+	var x;
+	var y;
+	var i;
+
+	opts = {
+		'dtype': 'float64'
+	};
+	x = uniform( 100, 0.0, 10.0, opts );
+	sigma = uniform( 100, EPS, 10.0, opts );
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		y = pdf( x[ i % x.length ], sigma[ i % sigma.length ] );
+		if ( isnan( y ) ) {
+			b.fail( 'should not return NaN' );
+		}
+	}
+	b.toc();
+	if ( isnan( y ) ) {
+		b.fail( 'should not return NaN' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/benchmark/c/Makefile b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/benchmark/c/Makefile
new file mode 100644
index 000000000000..979768abbcec
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/benchmark/c/Makefile
@@ -0,0 +1,146 @@
+#/
+# @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.
+#/
+
+# 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/stats/base/dists/halfnormal/pdf/benchmark/c/benchmark.c b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/benchmark/c/benchmark.c
new file mode 100644
index 000000000000..6503edb5411e
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/benchmark/c/benchmark.c
@@ -0,0 +1,141 @@
+/**
+* @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.
+*/
+
+#include "stdlib/stats/base/dists/halfnormal/pdf.h"
+#include "stdlib/constants/float64/eps.h"
+#include <stdlib.h>
+#include <stdio.h>
+#include <math.h>
+#include <time.h>
+#include <sys/time.h>
+
+#define NAME "halfnormal-pdf"
+#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 [min,max).
+*
+* @param min    minimum value (inclusive)
+* @param max    maximum value (exclusive)
+* @return       random number
+*/
+static double random_uniform( const double min, const double max ) {
+	double v = (double)rand() / ( (double)RAND_MAX + 1.0 );
+	return min + ( v*(max-min) );
+}
+
+/**
+* Runs a benchmark.
+*
+* @return elapsed time in seconds
+*/
+static double benchmark( void ) {
+	double elapsed;
+	double sigma[ 100 ];
+	double x[ 100 ];
+	double y;
+	double t;
+	int i;
+
+	for ( i = 0; i < 100; i++ ) {
+		x[ i ] = random_uniform( 0.0, 100.0 );
+		sigma[ i ] = random_uniform( STDLIB_CONSTANT_FLOAT64_EPS, 20.0 );
+	}
+
+	t = tic();
+	for ( i = 0; i < ITERATIONS; i++ ) {
+		y = stdlib_base_dists_halfnormal_pdf( x[ i%100 ], sigma[ 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::%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/stats/base/dists/halfnormal/pdf/binding.gyp b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/binding.gyp
new file mode 100644
index 000000000000..0d6508a12e99
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/binding.gyp
@@ -0,0 +1,170 @@
+# @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.
+
+# 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/stats/base/dists/halfnormal/pdf/docs/repl.txt b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/docs/repl.txt
new file mode 100644
index 000000000000..94458c4ecf2c
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/docs/repl.txt
@@ -0,0 +1,68 @@
+
+{{alias}}( x, sigma )
+    Evaluates the probability density function (PDF) for a half-normal
+    distribution with scale parameter `sigma` at a value `x`.
+
+    If provided `NaN` as any argument, the function returns `NaN`.
+
+    If provided `sigma <= 0`, the function returns `NaN`.
+
+    If provided a negative value for `x`, the function returns `0`.
+
+    Parameters
+    ----------
+    x: number
+        Input value.
+
+    sigma: number
+        Scale parameter.
+
+    Returns
+    -------
+    out: number
+        Evaluated PDF.
+
+    Examples
+    --------
+    > var y = {{alias}}( 0.0, 1.0 )
+    ~0.798
+    > y = {{alias}}( 2.0, 1.0 )
+    ~0.108
+    > y = {{alias}}( 0.5, 1.0 )
+    ~0.704
+    > y = {{alias}}( -1.0, 1.0 )
+    0.0
+    > y = {{alias}}( NaN, 1.0 )
+    NaN
+    > y = {{alias}}( 0.0, NaN )
+    NaN
+    // Negative scale parameter:
+    > y = {{alias}}( 2.0, -1.0 )
+    NaN
+
+
+{{alias}}.factory( sigma )
+    Returns a function for evaluating the probability density function (PDF)
+    of a half-normal distribution with scale parameter `sigma`.
+
+    Parameters
+    ----------
+    sigma: number
+        Scale parameter.
+
+    Returns
+    -------
+    pdf: Function
+        Probability density function (PDF).
+
+    Examples
+    --------
+    > var myPDF = {{alias}}.factory( 2.0 );
+    > var y = myPDF( 0.0 )
+    ~0.399
+    > y = myPDF( 2.0 )
+    ~0.242
+
+    See Also
+    --------
+
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/docs/types/index.d.ts b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/docs/types/index.d.ts
new file mode 100644
index 000000000000..a000ddbf13af
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/docs/types/index.d.ts
@@ -0,0 +1,115 @@
+/*
+* @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.
+*/
+
+// TypeScript Version: 4.1
+
+/**
+* Evaluates the probability density function (PDF) for a half-normal distribution.
+*
+* @param x - input value
+* @returns evaluated PDF
+*/
+type Unary = ( x: number ) => number;
+
+/**
+* Interface for the probability density function (PDF) of a half-normal distribution.
+*/
+interface PDF {
+	/**
+	* Evaluates the probability density function (PDF) for a half-normal distribution with scale parameter `sigma` at a value `x`.
+	*
+	* ## Notes
+	*
+	* -   If provided `sigma <= 0`, the function returns `NaN`.
+	* -   If provided a negative value for `x`, the function returns `0`.
+	*
+	* @param x - input value
+	* @param sigma - scale parameter
+	* @returns evaluated PDF
+	*
+	* @example
+	* var y = pdf( 0.0, 1.0 );
+	* // returns ~0.798
+	*
+	* @example
+	* var y = pdf( 2.0, 1.0 );
+	* // returns ~0.108
+	*
+	* @example
+	* var y = pdf( 0.5, 1.0 );
+	* // returns ~0.704
+	*
+	* @example
+	* var y = pdf( -1.0, 1.0 );
+	* // returns 0.0
+	*
+	* @example
+	* var y = pdf( NaN, 1.0 );
+	* // returns NaN
+	*
+	* @example
+	* var y = pdf( 0.0, NaN );
+	* // returns NaN
+	*
+	* @example
+	* // Negative scale parameter:
+	* var y = pdf( 2.0, -1.0 );
+	* // returns NaN
+	*/
+	( x: number, sigma: number ): number;
+
+	/**
+	* Returns a function for evaluating the probability density function (PDF) for a half-normal distribution with scale parameter `sigma`.
+	*
+	* @param sigma - scale parameter
+	* @returns PDF
+	*
+	* @example
+	* var myPDF = pdf.factory( 2.0 );
+	*
+	* var y = myPDF( 0.0 );
+	* // returns ~0.399
+	*
+	* y = myPDF( 2.0 );
+	* // returns ~0.242
+	*/
+	factory( sigma: number ): Unary;
+}
+
+/**
+* Half-normal distribution probability density function (PDF).
+*
+* @param x - input value
+* @param sigma - scale parameter
+* @returns evaluated PDF
+*
+* @example
+* var y = pdf( 2.0, 1.0 );
+* // returns ~0.108
+*
+* @example
+* var myPDF = pdf.factory( 2.0 );
+* var y = myPDF( 0.5 );
+* // returns ~0.387
+*/
+declare var pdf: PDF;
+
+
+// EXPORTS //
+
+export = pdf;
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/docs/types/test.ts b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/docs/types/test.ts
new file mode 100644
index 000000000000..8566905c5829
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/docs/types/test.ts
@@ -0,0 +1,99 @@
+/*
+* @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.
+*/
+
+import pdf = require( './index' );
+
+
+// TESTS //
+
+// The function returns a number...
+{
+	pdf( 2, 2 ); // $ExpectType number
+	pdf( 1, 8 ); // $ExpectType number
+}
+
+// The compiler throws an error if the function is provided values other than two numbers...
+{
+	pdf( true, 3 ); // $ExpectError
+	pdf( false, 2 ); // $ExpectError
+	pdf( '5', 1 ); // $ExpectError
+	pdf( [], 1 ); // $ExpectError
+	pdf( {}, 2 ); // $ExpectError
+	pdf( ( x: number ): number => x, 2 ); // $ExpectError
+
+	pdf( 9, true ); // $ExpectError
+	pdf( 9, false ); // $ExpectError
+	pdf( 5, '5' ); // $ExpectError
+	pdf( 8, [] ); // $ExpectError
+	pdf( 9, {} ); // $ExpectError
+	pdf( 8, ( x: number ): number => x ); // $ExpectError
+}
+
+// The compiler throws an error if the function is provided an unsupported number of arguments...
+{
+	pdf(); // $ExpectError
+	pdf( 2 ); // $ExpectError
+	pdf( 2, 0, 4 ); // $ExpectError
+}
+
+// Attached to main export is a `factory` method which returns a function...
+{
+	pdf.factory( 4 ); // $ExpectType Unary
+}
+
+// The `factory` method returns a function which returns a number...
+{
+	const fcn = pdf.factory( 4 );
+	fcn( 2 ); // $ExpectType number
+}
+
+// The compiler throws an error if the function returned by the `factory` method is provided invalid arguments...
+{
+	const fcn = pdf.factory( 4 );
+	fcn( true ); // $ExpectError
+	fcn( false ); // $ExpectError
+	fcn( '5' ); // $ExpectError
+	fcn( [] ); // $ExpectError
+	fcn( {} ); // $ExpectError
+	fcn( ( x: number ): number => x ); // $ExpectError
+}
+
+// The compiler throws an error if the function returned by the `factory` method is provided an unsupported number of arguments...
+{
+	const fcn = pdf.factory( 4 );
+	fcn(); // $ExpectError
+	fcn( 2, 0 ); // $ExpectError
+	fcn( 2, 0, 1 ); // $ExpectError
+}
+
+// The compiler throws an error if the `factory` method is provided values other than a number...
+{
+	pdf.factory( true ); // $ExpectError
+	pdf.factory( false ); // $ExpectError
+	pdf.factory( '5' ); // $ExpectError
+	pdf.factory( [] ); // $ExpectError
+	pdf.factory( {} ); // $ExpectError
+	pdf.factory( ( x: number ): number => x ); // $ExpectError
+}
+
+// The compiler throws an error if the `factory` method is provided an unsupported number of arguments...
+{
+	pdf.factory(); // $ExpectError
+	pdf.factory( 2, 0 ); // $ExpectError
+	pdf.factory( 2, 0, 1 ); // $ExpectError
+}
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/examples/c/Makefile b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/examples/c/Makefile
new file mode 100644
index 000000000000..c8f8e9a1517b
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/examples/c/Makefile
@@ -0,0 +1,146 @@
+#/
+# @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.
+#/
+
+# 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/stats/base/dists/halfnormal/pdf/examples/c/example.c b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/examples/c/example.c
new file mode 100644
index 000000000000..2b014e793952
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/examples/c/example.c
@@ -0,0 +1,40 @@
+/**
+* @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.
+*/
+
+#include "stdlib/stats/base/dists/halfnormal/pdf.h"
+#include <stdlib.h>
+#include <stdio.h>
+
+static double random_uniform( const double min, const double max ) {
+	double v = (double)rand() / ( (double)RAND_MAX + 1.0 );
+	return min + ( v*(max-min) );
+}
+
+int main( void ) {
+	double sigma;
+	double x;
+	double y;
+	int i;
+
+	for ( i = 0; i < 25; i++ ) {
+		x = random_uniform( 0.0, 10.0 );
+		sigma = random_uniform( 0.0, 10.0 );
+		y = stdlib_base_dists_halfnormal_pdf( x, sigma );
+		printf( "x: %lf, σ: %lf, f(x;σ): %lf\n", x, sigma, y );
+	}
+}
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/examples/index.js b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/examples/index.js
new file mode 100644
index 000000000000..fc5ee6cf0ed8
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/examples/index.js
@@ -0,0 +1,31 @@
+/**
+* @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';
+
+var uniform = require( '@stdlib/random/array/uniform' );
+var logEachMap = require( '@stdlib/console/log-each-map' );
+var pdf = require( './../lib' );
+
+var opts = {
+	'dtype': 'float64'
+};
+var x = uniform( 10, 0.0, 10.0, opts );
+var sigma = uniform( 10, 0.0, 10.0, opts );
+
+logEachMap( 'x: %lf, σ: %lf, f(x;σ): %lf', x, sigma, pdf );
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/include.gypi b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/include.gypi
new file mode 100644
index 000000000000..bee8d41a2caf
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/include.gypi
@@ -0,0 +1,53 @@
+# @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.
+
+# 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': [
+      '<!@(node -e "var arr = require(\'@stdlib/utils/library-manifest\')(\'./manifest.json\',{},{\'basedir\':process.cwd(),\'paths\':\'posix\'}).include; for ( var i = 0; i < arr.length; i++ ) { console.log( arr[ i ] ); }")',
+    ],
+
+    # Add-on destination directory:
+    'addon_output_dir': './src',
+
+    # Source files:
+    'src_files': [
+      '<(src_dir)/addon.c',
+      '<!@(node -e "var arr = require(\'@stdlib/utils/library-manifest\')(\'./manifest.json\',{},{\'basedir\':process.cwd(),\'paths\':\'posix\'}).src; for ( var i = 0; i < arr.length; i++ ) { console.log( arr[ i ] ); }")',
+    ],
+
+    # Library dependencies:
+    'libraries': [
+      '<!@(node -e "var arr = require(\'@stdlib/utils/library-manifest\')(\'./manifest.json\',{},{\'basedir\':process.cwd(),\'paths\':\'posix\'}).libraries; for ( var i = 0; i < arr.length; i++ ) { console.log( arr[ i ] ); }")',
+    ],
+
+    # Library directories:
+    'library_dirs': [
+      '<!@(node -e "var arr = require(\'@stdlib/utils/library-manifest\')(\'./manifest.json\',{},{\'basedir\':process.cwd(),\'paths\':\'posix\'}).libpath; for ( var i = 0; i < arr.length; i++ ) { console.log( arr[ i ] ); }")',
+    ],
+  }, # end variables
+}
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/include/stdlib/stats/base/dists/halfnormal/pdf.h b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/include/stdlib/stats/base/dists/halfnormal/pdf.h
new file mode 100644
index 000000000000..c5fc7feb7ea2
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/include/stdlib/stats/base/dists/halfnormal/pdf.h
@@ -0,0 +1,40 @@
+/**
+* @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.
+*/
+
+#ifndef STDLIB_STATS_BASE_DISTS_HALFNORMAL_PDF_H
+#define STDLIB_STATS_BASE_DISTS_HALFNORMAL_PDF_H
+
+
+/*
+* If C++, prevent name mangling so that the compiler emits a binary file with C-style linkage.
+*/
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+* Evaluates the probability density function (PDF) for a half-normal distribution.
+*/
+double stdlib_base_dists_halfnormal_pdf( const double x, const double sigma );
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // !STDLIB_STATS_BASE_DISTS_HALFNORMAL_PDF_H
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/lib/factory.js b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/lib/factory.js
new file mode 100644
index 000000000000..4cb3c1d0a880
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/lib/factory.js
@@ -0,0 +1,84 @@
+/**
+* @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 constantFunction = require( '@stdlib/utils/constant-function' );
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+var sqrt = require( '@stdlib/math/base/special/sqrt' );
+var exp = require( '@stdlib/math/base/special/exp' );
+var PI = require( '@stdlib/constants/float64/pi' );
+
+
+// MAIN //
+
+/**
+* Returns a function for evaluating the probability density function (PDF) for a half-normal distribution.
+*
+* @param {PositiveNumber} sigma - scale parameter
+* @returns {Function} function to evaluate the probability density function
+*
+* @example
+* var pdf = factory( 1.0 );
+* var y = pdf( 2.0 );
+* // returns ~0.108
+*
+* y = pdf( 1.0 );
+* // returns ~0.484
+*/
+function factory( sigma ) {
+	var A;
+	if (
+		isnan( sigma ) ||
+		sigma <= 0.0
+	) {
+		return constantFunction( NaN );
+	}
+	A = sqrt( 2.0 / PI ) / sigma;
+	return pdf;
+
+	/**
+	* Evaluates the probability density function (PDF) for a half-normal distribution.
+	*
+	* @private
+	* @param {number} x - input value
+	* @returns {number} evaluated probability density function
+	*
+	* @example
+	* var y = pdf( 0.5 );
+	* // returns <number>
+	*/
+	function pdf( x ) {
+		var C;
+		if ( isnan( x ) ) {
+			return NaN;
+		}
+		if ( x < 0.0 ) {
+			return 0.0;
+		}
+		C = x / sigma;
+		return A * exp( -0.5 * ( C*C ) );
+	}
+}
+
+
+// EXPORTS //
+
+module.exports = factory;
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/lib/index.js b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/lib/index.js
new file mode 100644
index 000000000000..60fad3c728b7
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/lib/index.js
@@ -0,0 +1,63 @@
+/**
+* @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';
+
+/**
+* Half-normal distribution probability density function (PDF).
+*
+* @module @stdlib/stats/base/dists/halfnormal/pdf
+*
+* @example
+* var pdf = require( '@stdlib/stats/base/dists/halfnormal/pdf' );
+*
+* var y = pdf( 2.0, 1.0 );
+* // returns ~0.108
+*
+* y = pdf( 0.5, 1.0 );
+* // returns ~0.704
+*
+* y = pdf( -1.0, 1.0 );
+* // returns 0.0
+*
+* @example
+* var pdfFactory = require( '@stdlib/stats/base/dists/halfnormal/pdf' ).factory;
+*
+* var pdf = pdfFactory( 1.0 );
+* var y = pdf( 2.0 );
+* // returns ~0.108
+*
+* y = pdf( 1.0 );
+* // returns ~0.484
+*/
+
+// MODULES //
+
+var setReadOnly = require( '@stdlib/utils/define-nonenumerable-read-only-property' );
+var main = require( './main.js' );
+var factory = require( './factory.js' );
+
+
+// MAIN //
+
+setReadOnly( main, 'factory', factory );
+
+
+// EXPORTS //
+
+module.exports = main;
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/lib/main.js b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/lib/main.js
new file mode 100644
index 000000000000..19a015661389
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/lib/main.js
@@ -0,0 +1,77 @@
+/**
+* @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 isnan = require( '@stdlib/math/base/assert/is-nan' );
+var exp = require( '@stdlib/math/base/special/exp' );
+var sqrt = require( '@stdlib/math/base/special/sqrt' );
+var PI = require( '@stdlib/constants/float64/pi' );
+
+
+// MAIN //
+
+/**
+* Evaluates the probability density function (PDF) for a half-normal distribution.
+*
+* @param {number} x - input value
+* @param {PositiveNumber} sigma - scale parameter
+* @returns {number} evaluated PDF
+*
+* @example
+* var y = pdf( 2.0, 1.0 );
+* // returns ~0.108
+*
+* @example
+* var y = pdf( 0.5, 1.0 );
+* // returns ~0.704
+*
+* @example
+* var y = pdf( -1.0, 1.0 );
+* // returns 0.0
+*
+* @example
+* var y = pdf( NaN, 1.0 );
+* // returns NaN
+*
+* @example
+* var y = pdf( 0.0, NaN );
+* // returns NaN
+*
+* @example
+* var y = pdf( 0.0, -1.0 );
+* // returns NaN
+*/
+function pdf( x, sigma ) {
+	var C;
+	if ( isnan( x ) || isnan( sigma ) || sigma <= 0.0 ) {
+		return NaN;
+	}
+	if ( x < 0.0 ) {
+		return 0.0;
+	}
+	C = x / sigma;
+	return ( sqrt( 2.0 / PI ) * exp( -0.5 * ( C*C ) ) / sigma );
+}
+
+
+// EXPORTS //
+
+module.exports = pdf;
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/lib/native.js b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/lib/native.js
new file mode 100644
index 000000000000..14355d745477
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/lib/native.js
@@ -0,0 +1,55 @@
+/**
+* @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 addon = require( './../src/addon.node' );
+
+
+// MAIN //
+
+/**
+* Evaluates the probability density function (PDF) for a half-normal distribution.
+*
+* @private
+* @param {number} x - input value
+* @param {PositiveNumber} sigma - scale parameter
+* @returns {number} evaluated PDF
+*
+* @example
+* var y = pdf( 2.0, 1.0 );
+* // returns ~0.108
+*
+* @example
+* var y = pdf( 0.5, 1.0 );
+* // returns ~0.704
+*
+* @example
+* var y = pdf( -1.0, 1.0 );
+* // returns 0.0
+*/
+function pdf( x, sigma ) {
+	return addon( x, sigma );
+}
+
+
+// EXPORTS //
+
+module.exports = pdf;
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/manifest.json b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/manifest.json
new file mode 100644
index 000000000000..6a5815255b3a
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/manifest.json
@@ -0,0 +1,86 @@
+{
+  "options": {
+    "task": "build",
+    "wasm": false
+  },
+  "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",
+      "wasm": false,
+      "src": [
+        "./src/pdf.c"
+      ],
+      "include": [
+        "./include"
+      ],
+      "libraries": [],
+      "libpath": [],
+      "dependencies": [
+        "@stdlib/math/base/napi/binary",
+        "@stdlib/math/base/special/sqrt",
+        "@stdlib/math/base/special/exp",
+        "@stdlib/constants/float64/pi",
+        "@stdlib/math/base/assert/is-nan"
+      ]
+    },
+    {
+      "task": "benchmark",
+      "wasm": false,
+      "src": [
+        "./src/pdf.c"
+      ],
+      "include": [
+        "./include"
+      ],
+      "libraries": [],
+      "libpath": [],
+      "dependencies": [
+        "@stdlib/constants/float64/eps",
+        "@stdlib/math/base/special/sqrt",
+        "@stdlib/math/base/special/exp",
+        "@stdlib/constants/float64/pi",
+        "@stdlib/math/base/assert/is-nan"
+      ]
+    },
+    {
+      "task": "examples",
+      "wasm": false,
+      "src": [
+        "./src/pdf.c"
+      ],
+      "include": [
+        "./include"
+      ],
+      "libraries": [],
+      "libpath": [],
+      "dependencies": [
+        "@stdlib/math/base/special/sqrt",
+        "@stdlib/math/base/special/exp",
+        "@stdlib/constants/float64/pi",
+        "@stdlib/math/base/assert/is-nan"
+      ]
+    }
+  ]
+}
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/package.json b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/package.json
new file mode 100644
index 000000000000..ec8a756da706
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/package.json
@@ -0,0 +1,67 @@
+{
+  "name": "@stdlib/stats/base/dists/halfnormal/pdf",
+  "version": "0.0.0",
+  "description": "Half-normal distribution probability density function (PDF).",
+  "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",
+    "statistics",
+    "stats",
+    "distribution",
+    "dist",
+    "continuous",
+    "probability",
+    "pdf",
+    "half-normal",
+    "univariate"
+  ]
+}
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/src/Makefile b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/src/Makefile
new file mode 100644
index 000000000000..2caf905cedbe
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/src/Makefile
@@ -0,0 +1,70 @@
+#/
+# @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.
+#/
+
+# 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/stats/base/dists/halfnormal/pdf/src/addon.c b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/src/addon.c
new file mode 100644
index 000000000000..27ab9192b45b
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/src/addon.c
@@ -0,0 +1,22 @@
+/**
+* @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.
+*/
+
+#include "stdlib/stats/base/dists/halfnormal/pdf.h"
+#include "stdlib/math/base/napi/binary.h"
+
+STDLIB_MATH_BASE_NAPI_MODULE_DD_D( stdlib_base_dists_halfnormal_pdf )
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/src/pdf.c b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/src/pdf.c
new file mode 100644
index 000000000000..6acc67b51eda
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/src/pdf.c
@@ -0,0 +1,46 @@
+/**
+* @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.
+*/
+
+#include "stdlib/stats/base/dists/halfnormal/pdf.h"
+#include "stdlib/math/base/assert/is_nan.h"
+#include "stdlib/math/base/special/exp.h"
+#include "stdlib/math/base/special/sqrt.h"
+#include "stdlib/constants/float64/pi.h"
+
+/**
+* Evaluates the probability density function (PDF) for a half-normal distribution.
+*
+* @param x        input value
+* @param sigma    scale parameter
+* @return         evaluated PDF
+*
+* @example
+* double y = stdlib_base_dists_halfnormal_pdf( 2.0, 1.0 );
+* // returns ~0.108
+*/
+double stdlib_base_dists_halfnormal_pdf( const double x, const double sigma ) {
+	double C;
+	if ( stdlib_base_is_nan( x ) || stdlib_base_is_nan( sigma ) || sigma <= 0.0 ) {
+		return 0.0/0.0; // NaN
+	}
+	if ( x < 0.0 ) {
+		return 0.0;
+	}
+	C = x / sigma;
+	return ( stdlib_base_sqrt( 2.0 / STDLIB_CONSTANT_FLOAT64_PI ) * stdlib_base_exp( -0.5 * ( C*C ) ) / sigma );
+}
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/test/fixtures/julia/REQUIRE b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/test/fixtures/julia/REQUIRE
new file mode 100644
index 000000000000..98be20b58ed3
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/test/fixtures/julia/REQUIRE
@@ -0,0 +1,3 @@
+Distributions 0.23.8
+julia 1.5
+JSON 0.21
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/test/fixtures/julia/data.json b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/test/fixtures/julia/data.json
new file mode 100644
index 000000000000..ef979174aa29
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/test/fixtures/julia/data.json
@@ -0,0 +1 @@
+{"sigma":[0.0005027698928828538,8.33977450663294,1.739351630272375,0.013923919808057544,0.00017166006949722202,0.2250113561914013,0.0006836575750694594,3.851728262627637e-5,0.0003942374504325936,0.0013133910521928235],"expected":[540.8742605176662,0.07673827634595597,7.408574432093552e-17,42.17094618038342,0.00021875574190708885,0.11019944114042587,0.3904045154336773,1.6635539205950216e-9,0.009225932289574298,2.357160749519236e-19],"x":[0.0007376851835890518,5.538603976641584,14.832907764838476,0.010903846598781639,0.0009971590797320585,0.5928762313212765,0.0027351146104325525,0.00029911303439581356,0.001955235159985202,0.013041782749973967]}
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/test/fixtures/julia/runner.jl b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/test/fixtures/julia/runner.jl
new file mode 100644
index 000000000000..38388dbb3665
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/test/fixtures/julia/runner.jl
@@ -0,0 +1,93 @@
+#!/usr/bin/env julia
+#
+# @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.
+
+using Distributions
+using JSON
+using Random
+
+"""
+	halfnormal_pdf( x, sigma )
+
+Evaluate the half-normal probability density function.
+
+The half-normal distribution is defined as
+
+	X = |Z|,   where Z ~ Normal(0, σ)
+
+which is equivalent to a truncated normal distribution
+
+	Truncated( Normal(0, σ), 0, ∞ ).
+"""
+halfnormal_pdf( x, sigma ) = pdf( Truncated( Normal( 0.0, sigma ), 0.0, Inf ), x )
+
+"""
+	logrand( a, b )
+
+Generate a log-uniform random number in the interval [a, b].
+"""
+logrand( a, b ) = exp( rand()*( log(b)-log(a) ) + log(a) )
+
+"""
+	gen( n, name )
+
+Generate randomized half-normal PDF fixture data and write to file.
+
+# Arguments
+
+* `n::Integer`: number of random samples
+* `name::AbstractString`: output filename
+"""
+function gen( n, name )
+	X = Float64[]
+	S = Float64[]
+	Z = Float64[]
+
+	# Ensure reproducibility:
+	Random.seed!( 123456 )
+
+	for i in 1:n
+		# σ spans many orders of magnitude:
+		sigma = logrand( 1.0e-6, 10.0 )
+
+		# Sample x in units of σ to avoid trivial underflow:
+		x = rand() * 10.0 * sigma
+
+		push!( X, x )
+		push!( S, sigma )
+		push!( Z, halfnormal_pdf( x, sigma ) )
+	end
+
+	# Store data to be written to file:
+	data = Dict([
+		( "x", X ),
+		( "sigma", S ),
+		( "expected", Z )
+	])
+
+	# Output path relative to this script:
+	filepath = joinpath( dirname(@__FILE__), name )
+
+	# Write JSON:
+	open( filepath, "w" ) do io
+		write( io, JSON.json( data ) )
+		write( io, "\n" )
+	end
+end
+
+# Generate randomized fixtures:
+gen( 10, "data.json" )
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/test/test.factory.js b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/test/test.factory.js
new file mode 100644
index 000000000000..48aa24efd0d6
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/test/test.factory.js
@@ -0,0 +1,163 @@
+/**
+* @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 tape = require( 'tape' );
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+var abs = require( '@stdlib/math/base/special/abs' );
+var PINF = require( '@stdlib/constants/float64/pinf' );
+var NINF = require( '@stdlib/constants/float64/ninf' );
+var EPS = require( '@stdlib/constants/float64/eps' );
+var factory = require( './../lib/factory.js' );
+
+
+// FIXTURES //
+
+var data = require( './fixtures/julia/data.json' );
+
+
+// TESTS //
+
+tape( 'main export is a function', function test( t ) {
+	t.ok( true, __filename );
+	t.strictEqual( typeof factory, 'function', 'main export is a function' );
+	t.end();
+});
+
+tape( 'the function returns a function', function test( t ) {
+	var pdf = factory( 1.0 );
+	t.strictEqual( typeof pdf, 'function', 'returns expected value' );
+	t.end();
+});
+
+tape( 'if provided `NaN` for any parameter, the created function returns `NaN`', function test( t ) {
+	var pdf;
+	var y;
+
+	pdf = factory( 1.0 );
+	y = pdf( NaN );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	pdf = factory( NaN );
+	y = pdf( 0.0 );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	pdf = factory( NaN );
+	y = pdf( NaN );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	t.end();
+});
+
+tape( 'if provided a finite `sigma`, the function returns a function which returns `0` when provided `+infinity` for `x`', function test( t ) {
+	var pdf;
+	var y;
+
+	pdf = factory( 1.0 );
+	y = pdf( PINF );
+	t.strictEqual( y, 0.0, 'returns expected value' );
+
+	t.end();
+});
+
+tape( 'if provided a finite `sigma`, the function returns a function which returns `0` when provided `-infinity` for `x`', function test( t ) {
+	var pdf;
+	var y;
+
+	pdf = factory( 1.0 );
+	y = pdf( NINF );
+	t.strictEqual( y, 0.0, 'returns expected value' );
+
+	t.end();
+});
+
+tape( 'if provided a negative `sigma`, the created function always returns `NaN`', function test( t ) {
+	var pdf;
+	var y;
+
+	pdf = factory( -1.0 );
+
+	y = pdf( 2.0 );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	y = pdf( 0.0 );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	pdf = factory( NINF );
+	y = pdf( 2.0 );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	t.end();
+});
+
+tape( 'if `sigma` equals `0`, the created function always returns `NaN`', function test( t ) {
+	var pdf;
+	var y;
+
+	pdf = factory( 0.0 );
+
+	y = pdf( 0.0 );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	y = pdf( 1.0 );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	y = pdf( -1.0 );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	y = pdf( PINF );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	y = pdf( NINF );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	y = pdf( NaN );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	t.end();
+});
+
+tape( 'the created function evaluates the pdf for `x` given parameter `sigma`', function test( t ) {
+	var expected;
+	var delta;
+	var sigma;
+	var pdf;
+	var tol;
+	var x;
+	var y;
+	var i;
+
+	expected = data.expected;
+	x = data.x;
+	sigma = data.sigma;
+	for ( i = 0; i < x.length; i++ ) {
+		pdf = factory( sigma[i] );
+		y = pdf( x[i] );
+		if ( y === expected[i] ) {
+			t.strictEqual( y, expected[i], 'x: '+x[i]+', sigma: '+sigma[i]+', y: '+y+', expected: '+expected[i] );
+		} else {
+			delta = abs( y - expected[ i ] );
+			tol = 40.0 * EPS * abs( expected[ i ] );
+			t.ok( delta <= tol, 'within tolerance. x: '+x[ i ]+'. sigma: '+sigma[i]+'. y: '+y+'. E: '+expected[ i ]+'. Δ: '+delta+'. tol: '+tol+'.' );
+		}
+	}
+	t.end();
+});
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/test/test.js b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/test/test.js
new file mode 100644
index 000000000000..f21fbd456392
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/test/test.js
@@ -0,0 +1,94 @@
+/**
+* @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 tape = require( 'tape' );
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+var abs = require( '@stdlib/math/base/special/abs' );
+var EPS = require( '@stdlib/constants/float64/eps' );
+var pdf = require( './../lib' );
+
+
+// FIXTURES //
+
+var data = require( './fixtures/julia/data.json' );
+
+
+// TESTS //
+
+tape( 'main export is a function', function test( t ) {
+	t.ok( true, __filename );
+	t.strictEqual( typeof pdf, 'function', 'main export is a function' );
+	t.end();
+});
+
+tape( 'if provided `NaN` for any parameter, the function returns `NaN`', function test( t ) {
+	var y = pdf( NaN, 1.0 );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	y = pdf( 0.0, NaN );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	t.end();
+});
+
+tape( 'if provided `sigma <= 0`, the function returns `NaN`', function test( t ) {
+	var y;
+
+	y = pdf( 2.0, -1.0 );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+	y = pdf( 2.0, 0.0 );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	t.end();
+});
+
+tape( 'if provided `x < 0`, the function returns `0`', function test( t ) {
+	var y = pdf( -1.0, 1.0 );
+	t.strictEqual( y, 0.0, 'returns expected value' );
+
+	t.end();
+});
+
+tape( 'the function evaluates the half-normal pdf', function test( t ) {
+	var expected;
+	var delta;
+	var sigma;
+	var tol;
+	var x;
+	var i;
+	var y;
+
+	expected = data.expected;
+	x = data.x;
+	sigma = data.sigma;
+	for ( i = 0; i < expected.length; i++ ) {
+		y = pdf( x[i], sigma[i] );
+		if ( y === expected[i] ) {
+			t.strictEqual( y, expected[i], 'x: '+x[i]+', sigma: '+sigma[i]+', y: '+y+', expected: '+expected[i] );
+		} else {
+			delta = abs( y - expected[ i ] );
+			tol = 40.0 * EPS * abs( expected[ i ] );
+			t.ok( delta <= tol, 'within tolerance. x: ' + x[i] + ', sigma: ' + sigma[i] + '. y: ' + y + '. E: ' + expected[ i ] + '. Δ: ' + delta + '. tol: ' + tol + '.' );
+		}
+	}
+	t.end();
+});
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/test/test.native.js b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/test/test.native.js
new file mode 100644
index 000000000000..fb1a4f6d4f57
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/test/test.native.js
@@ -0,0 +1,103 @@
+/**
+* @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 tape = require( 'tape' );
+var tryRequire = require( '@stdlib/utils/try-require' );
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+var abs = require( '@stdlib/math/base/special/abs' );
+var EPS = require( '@stdlib/constants/float64/eps' );
+
+
+// FIXTURES //
+
+var data = require( './fixtures/julia/data.json' );
+
+
+// VARIABLES //
+
+var pdf = tryRequire( resolve( __dirname, './../lib/native.js' ) );
+var opts = {
+	'skip': ( pdf instanceof Error )
+};
+
+
+// TESTS //
+
+tape( 'main export is a function', opts, function test( t ) {
+	t.ok( true, __filename );
+	t.strictEqual( typeof pdf, 'function', 'main export is a function' );
+	t.end();
+});
+
+tape( 'if provided `NaN` for any parameter, the function returns `NaN`', opts, function test( t ) {
+	var y = pdf( NaN, 1.0 );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	y = pdf( 0.0, NaN );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	t.end();
+});
+
+tape( 'if provided `sigma <= 0`, the function returns `NaN`', opts, function test( t ) {
+	var y;
+
+	y = pdf( 2.0, -1.0 );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+	y = pdf( 2.0, 0.0 );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	t.end();
+});
+
+tape( 'if provided `x < 0`, the function returns `0`', opts, function test( t ) {
+	var y = pdf( -1.0, 1.0 );
+	t.strictEqual( y, 0.0, 'returns expected value' );
+
+	t.end();
+});
+
+tape( 'the function evaluates the half-normal pdf', opts, function test( t ) {
+	var expected;
+	var delta;
+	var sigma;
+	var tol;
+	var x;
+	var i;
+	var y;
+
+	expected = data.expected;
+	x = data.x;
+	sigma = data.sigma;
+	for ( i = 0; i < expected.length; i++ ) {
+		y = pdf( x[i], sigma[i] );
+		if ( y === expected[i] ) {
+			t.strictEqual( y, expected[i], 'x: '+x[i]+', sigma: '+sigma[i]+', y: '+y+', expected: '+expected[i] );
+		} else {
+			delta = abs( y - expected[ i ] );
+			tol = 40.0 * EPS * abs( expected[ i ] );
+			t.ok( delta <= tol, 'within tolerance. x: ' + x[i] + ', sigma: ' + sigma[i] + '. y: ' + y + '. E: ' + expected[ i ] + '. Δ: ' + delta + '. tol: ' + tol + '.' );
+		}
+	}
+	t.end();
+});
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/test/test.pdf.js b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/test/test.pdf.js
new file mode 100644
index 000000000000..8e714499b96e
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/pdf/test/test.pdf.js
@@ -0,0 +1,134 @@
+/**
+* @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 tape = require( 'tape' );
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+var abs = require( '@stdlib/math/base/special/abs' );
+var PINF = require( '@stdlib/constants/float64/pinf' );
+var NINF = require( '@stdlib/constants/float64/ninf' );
+var EPS = require( '@stdlib/constants/float64/eps' );
+var pdf = require( './../lib' );
+
+
+// FIXTURES //
+
+var data = require( './fixtures/julia/data.json' );
+
+
+// TESTS //
+
+tape( 'main export is a function', function test( t ) {
+	t.ok( true, __filename );
+	t.strictEqual( typeof pdf, 'function', 'main export is a function' );
+	t.end();
+});
+
+tape( 'if provided `NaN` for any parameter, the function returns `NaN`', function test( t ) {
+	var y;
+
+	y = pdf( NaN, 1.0 );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	y = pdf( 0.0, NaN );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	y = pdf( NaN, NaN );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	t.end();
+});
+
+tape( 'if provided a negative value for `x`, the function returns `0`', function test( t ) {
+	var y = pdf( -1.0, 1.0 );
+	t.strictEqual( y, 0.0, 'returns expected value' );
+	t.end();
+});
+
+tape( 'if provided `+infinity` for `x` and a finite `sigma`, the function returns `0`', function test( t ) {
+	var y = pdf( PINF, 1.0 );
+	t.strictEqual( y, 0.0, 'returns expected value' );
+	t.end();
+});
+
+tape( 'if provided a negative `sigma`, the function always returns `NaN`', function test( t ) {
+	var y;
+
+	y = pdf( 2.0, -1.0 );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	y = pdf( 0.0, -1.0 );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	y = pdf( 2.0, NINF );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	t.end();
+});
+
+tape( 'if provided `sigma` equals `0`, the function always returns `NaN`', function test( t ) {
+	var y;
+
+	y = pdf( 0.0, 0.0 );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	y = pdf( 1.0, 0.0 );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	y = pdf( -1.0, 0.0 );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	y = pdf( PINF, 0.0 );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	y = pdf( NINF, 0.0 );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	y = pdf( NaN, 0.0 );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+	t.end();
+});
+
+tape( 'the function evaluates the pdf for `x` given parameter `sigma`', function test( t ) {
+	var expected;
+	var delta;
+	var sigma;
+	var tol;
+	var x;
+	var y;
+	var i;
+
+	expected = data.expected;
+	x = data.x;
+	sigma = data.sigma;
+	for ( i = 0; i < x.length; i++ ) {
+		y = pdf( x[i], sigma[i] );
+		if ( y === expected[i] ) {
+			t.strictEqual( y, expected[i], 'x: '+x[i]+', sigma: '+sigma[i]+', y: '+y+', expected: '+expected[i] );
+		} else {
+			delta = abs( y - expected[ i ] );
+			tol = 40 * EPS * abs( expected[ i ] );
+			t.ok( delta <= tol, 'within tolerance. x: '+x[ i ]+'. sigma: '+sigma[i]+'. y: '+y+'. E: '+expected[ i ]+'. Δ: '+delta+'. tol: '+tol+'.' );
+		}
+	}
+	t.end();
+});