diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/README.md b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/README.md
new file mode 100644
index 000000000000..e77c980c5305
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/README.md
@@ -0,0 +1,247 @@
+
+
+# Logarithm of Probability Density Function
+
+> [Half-Normal][half-normal-distribution] distribution logarithm of [probability density function (PDF)][pdf].
+
+
+
+The [probability density function][pdf] (PDF) for a [half-normal][half-normal-distribution] random variable is
+
+
+
+```math
+f(x;\sigma) = \frac{\sqrt{2}}{\sigma\sqrt{\pi}} e^{-\frac{x^2}{2\sigma^2}}
+```
+
+
+
+
+
+for `x >= 0`, where `sigma > 0` is the scale parameter. For `x < 0`, the PDF is `0`.
+
+
+
+
+
+
+
+## Usage
+
+```javascript
+var logpdf = require( '@stdlib/stats/base/dists/halfnormal/logpdf' );
+```
+
+#### logpdf( x, sigma )
+
+Evaluates the logarithm of the [probability density function][pdf] (PDF) for a [half-normal][half-normal-distribution] distribution with parameter `sigma` (scale parameter).
+
+```javascript
+var y = logpdf( 0.8, 1.0 );
+// returns ~-0.546
+
+y = logpdf( 0.5, 1.0 );
+// returns ~-0.351
+
+y = logpdf( 1.2, 2.0 );
+// returns ~-1.099
+```
+
+If `x < 0`, the function returns `-Infinity`.
+
+```javascript
+var y = logpdf( -0.2, 1.0 );
+// returns -Infinity
+```
+
+If provided `NaN` as any argument, the function returns `NaN`.
+
+```javascript
+var y = logpdf( NaN, 1.0 );
+// returns NaN
+
+y = logpdf( 0.0, NaN );
+// returns NaN
+```
+
+If provided `sigma <= 0`, the function returns `NaN`.
+
+```javascript
+var y = logpdf( 2.0, -1.0 );
+// returns NaN
+
+y = logpdf( 2.0, 0.0 );
+// returns NaN
+```
+
+#### logpdf.factory( sigma )
+
+Returns a `function` for evaluating the logarithm of the [PDF][pdf] for a [half-normal][half-normal-distribution] distribution with parameter `sigma` (scale parameter).
+
+```javascript
+var mylogpdf = logpdf.factory( 1.0 );
+
+var y = mylogpdf( 0.8 );
+// returns ~-0.546
+
+y = mylogpdf( 1.2 );
+// returns ~-0.946
+```
+
+
+
+
+
+
+
+## Notes
+
+- In virtually all cases, using the `logpdf` or `logcdf` functions is preferable to manually computing the logarithm of the `pdf` or `cdf`, respectively, since the latter is prone to overflow and underflow.
+
+
+
+
+
+
+
+## Examples
+
+
+
+```javascript
+var randu = require( '@stdlib/random/base/randu' );
+var logpdf = require( '@stdlib/stats/base/dists/halfnormal/logpdf' );
+var i;
+var x;
+var y;
+var sigma;
+
+for ( i = 0; i < 25; i++ ) {
+ x = randu() * 3.0;
+ sigma = randu() * 3.0;
+ y = logpdf( x, sigma );
+ console.log( 'x: %d, σ: %d, ln(f(x;σ)): %d', x.toFixed( 4 ), sigma.toFixed( 4 ), y.toFixed( 4 ) );
+}
+```
+
+
+
+
+
+
+
+
+
+### Usage
+
+```c
+#include "stdlib/stats/base/dists/halfnormal/logpdf.h"
+```
+
+#### stdlib_base_dists_halfnormal_logpdf( x, sigma )
+
+Evaluates the logarithm of the [probability density function][pdf] (PDF) for a [Half-Normal][half-normal-distribution] distribution with parameter `sigma` (scale parameter).
+
+```c
+double out = stdlib_base_dists_halfnormal_logpdf( 0.8, 1.0 );
+// returns ~-0.546
+```
+
+The function accepts the following arguments:
+
+- **x**: `[in] double` input value.
+- **sigma**: `[in] double` scale parameter.
+
+```c
+double stdlib_base_dists_halfnormal_logpdf( const double x, const double sigma );
+```
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+### Examples
+
+```c
+#include "stdlib/stats/base/dists/halfnormal/logpdf.h"
+#include
+#include
+
+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( 0.1, 10.0 ); // sigma must be > 0
+ y = stdlib_base_dists_halfnormal_logpdf( x, sigma );
+ printf( "x: %lf, σ: %lf, ln(f(x;σ)): %lf\n", x, sigma, y );
+ }
+}
+```
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+[half-normal-distribution]: https://en.wikipedia.org/wiki/Half-normal_distribution
+
+[pdf]: https://en.wikipedia.org/wiki/Probability_density_function
+
+
+
+
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/benchmark/benchmark.js b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/benchmark/benchmark.js
new file mode 100644
index 000000000000..f1566e5b70b1
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/benchmark/benchmark.js
@@ -0,0 +1,93 @@
+/**
+* @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 Float64Array = require( '@stdlib/array/float64' );
+var uniform = require( '@stdlib/random/base/uniform' );
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+var EPS = require( '@stdlib/constants/float64/eps' );
+var pkg = require( './../package.json' ).name;
+var logpdf = require( './../lib' );
+
+
+// MAIN //
+
+bench( pkg, function benchmark( b ) {
+ var sigma;
+ var len;
+ var x;
+ var y;
+ var i;
+
+ len = 100;
+ x = new Float64Array( len );
+ sigma = new Float64Array( len );
+ for ( i = 0; i < len; i++ ) {
+ x[ i ] = uniform( 0.0, 10.0 );
+ sigma[ i ] = uniform( EPS, 10.0 );
+ }
+
+ b.tic();
+ for ( i = 0; i < b.iterations; i++ ) {
+ y = logpdf( x[ i % len ], sigma[ i % len ] );
+ 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 mylogpdf;
+ var sigma;
+ var len;
+ var x;
+ var y;
+ var i;
+
+ sigma = 4.0;
+ mylogpdf = logpdf.factory( sigma );
+ len = 100;
+ x = new Float64Array( len );
+ for ( i = 0; i < len; i++ ) {
+ x[ i ] = uniform( 0.0, 20.0 );
+ }
+
+ b.tic();
+ for ( i = 0; i < b.iterations; i++ ) {
+ y = mylogpdf( x[ i % len ] );
+ 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/logpdf/benchmark/benchmark.native.js b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/benchmark/benchmark.native.js
new file mode 100644
index 000000000000..0fe2269163a1
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/benchmark/benchmark.native.js
@@ -0,0 +1,71 @@
+/**
+* @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 Float64Array = require( '@stdlib/array/float64' );
+var randu = require( '@stdlib/random/base/randu' );
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+var EPS = require( '@stdlib/constants/float64/eps' );
+var tryRequire = require( '@stdlib/utils/try-require' );
+var pkg = require( './../package.json' ).name;
+
+
+// VARIABLES //
+
+var logpdf = tryRequire( resolve( __dirname, './../lib/native.js' ) );
+var opts = {
+ 'skip': ( logpdf instanceof Error )
+};
+
+
+// MAIN //
+
+bench( pkg+'::native', opts, function benchmark( b ) {
+ var sigma;
+ var len;
+ var x;
+ var y;
+ var i;
+
+ len = 100;
+ sigma = new Float64Array( len );
+ x = new Float64Array( len );
+ for ( i = 0; i < len; i++ ) {
+ x[ i ] = randu() * 10.0;
+ sigma[ i ] = ( randu() * 10.0 ) + EPS;
+ }
+
+ b.tic();
+ for ( i = 0; i < b.iterations; i++ ) {
+ y = logpdf( x[ i % len ], sigma[ i % len ] );
+ 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/logpdf/benchmark/c/Makefile b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/benchmark/c/Makefile
new file mode 100644
index 000000000000..34fcc0fcd245
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/benchmark/c/Makefile
@@ -0,0 +1,148 @@
+#/
+# @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/logpdf/benchmark/c/benchmark.c b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/benchmark/c/benchmark.c
new file mode 100644
index 000000000000..d9e0a57fb469
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/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/logpdf.h"
+#include "stdlib/constants/float64/eps.h"
+#include
+#include
+#include
+#include
+#include
+
+#define NAME "halfnormal-logpdf"
+#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, 10.0 );
+ sigma[ i ] = random_uniform( STDLIB_CONSTANT_FLOAT64_EPS, 10.0 );
+ }
+
+ t = tic();
+ for ( i = 0; i < ITERATIONS; i++ ) {
+ y = stdlib_base_dists_halfnormal_logpdf( 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/logpdf/binding.gyp b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/binding.gyp
new file mode 100644
index 000000000000..0d6508a12e99
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/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/logpdf/docs/repl.txt b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/docs/repl.txt
new file mode 100644
index 000000000000..c3e158932916
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/docs/repl.txt
@@ -0,0 +1,66 @@
+
+{{alias}}( x, σ )
+ Evaluates the logarithm of the probability density function (PDF) for a
+ half-normal distribution with scale parameter `σ` at a value `x`.
+
+ If provided `NaN` as any argument, the function returns `NaN`.
+
+ If provided `σ <= 0`, the function returns `NaN`.
+
+ If `x < 0`, the function returns `-Infinity`.
+
+ Parameters
+ ----------
+ x: number
+ Input value.
+
+ σ: number
+ Scale parameter.
+
+ Returns
+ -------
+ out: number
+ Evaluated logPDF.
+
+ Examples
+ --------
+ > var y = {{alias}}( 0.8, 1.0 )
+ ~-0.546
+ > y = {{alias}}( 0.5, 1.0 )
+ ~-0.351
+ > y = {{alias}}( 1.2, 2.0 )
+ ~-1.099
+ > y = {{alias}}( NaN, 1.0 )
+ NaN
+ > y = {{alias}}( 0.0, NaN )
+ NaN
+ // Negative scale parameter:
+ > y = {{alias}}( 2.0, -1.0 )
+ NaN
+
+
+{{alias}}.factory( σ )
+ Returns a function for evaluating the logarithm of the probability density
+ function (PDF) of a half-normal distribution with scale parameter `σ`.
+
+ Parameters
+ ----------
+ σ: number
+ Scale parameter.
+
+ Returns
+ -------
+ logpdf: Function
+ Logarithm of probability density function (PDF).
+
+ Examples
+ --------
+ > var mylogpdf = {{alias}}.factory( 1.0 );
+ > var y = mylogpdf( 0.8 )
+ ~-0.546
+ > y = mylogpdf( 1.2 )
+ ~-0.946
+
+ See Also
+ --------
+
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/docs/types/index.d.ts b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/docs/types/index.d.ts
new file mode 100644
index 000000000000..e72e44b43007
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/docs/types/index.d.ts
@@ -0,0 +1,106 @@
+/*
+* @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 natural logarithm of the probability density function (logPDF) for a half-normal distribution.
+*
+* @param x - input value
+* @returns evaluated logPDF
+*/
+type Unary = ( x: number ) => number;
+
+/**
+* Interface for the natural logarithm of the probability density function (logPDF) of a half-normal distribution.
+*/
+interface LogPDF {
+ /**
+ * Evaluates the logarithm of the probability density function (PDF) for a half-normal distribution with scale parameter `sigma`.
+ *
+ * ## Notes
+ *
+ * - If provided `sigma <= 0`, the function returns `NaN`.
+ * - If `x < 0`, the function returns `-Infinity`.
+ *
+ * @param x - input value
+ * @param sigma - scale parameter
+ * @returns evaluated logarithm of PDF
+ *
+ * @example
+ * var y = logpdf( 0.8, 1.0 );
+ * // returns ~-0.546
+ *
+ * @example
+ * var y = logpdf( 0.5, 1.0 );
+ * // returns ~-0.351
+ *
+ * @example
+ * var y = logpdf( 1.2, 2.0 );
+ * // returns ~-1.099
+ *
+ * @example
+ * var y = logpdf( NaN, 1.0 );
+ * // returns NaN
+ *
+ * @example
+ * var y = logpdf( 0.0, NaN );
+ * // returns NaN
+ *
+ * @example
+ * // Negative scale parameter:
+ * var y = logpdf( 2.0, -1.0 );
+ * // returns NaN
+ */
+ ( x: number, sigma: number ): number;
+
+ /**
+ * Returns a function for evaluating the logarithm of the probability density function (PDF) for a half-normal distribution with scale parameter `sigma`.
+ *
+ * @param sigma - scale parameter
+ * @returns logPDF
+ *
+ * @example
+ * var mylogpdf = logpdf.factory( 1.0 );
+ * var y = mylogpdf( 0.8 );
+ * // returns ~-0.546
+ */
+ factory( sigma: number ): Unary;
+}
+
+/**
+* Half-normal distribution natural logarithm of probability density function (logPDF).
+*
+* @param x - input value
+* @param sigma - scale parameter
+* @returns evaluated logPDF
+*
+* @example
+* var y = logpdf( 0.8, 1.0 );
+* // returns ~-0.546
+*
+* var mylogpdf = logpdf.factory( 1.0 );
+* var y = mylogpdf( 0.8 );
+* // returns ~-0.546
+*/
+declare var logpdf: LogPDF;
+
+
+// EXPORTS //
+
+export = logpdf;
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/docs/types/test.ts b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/docs/types/test.ts
new file mode 100644
index 000000000000..79c141e250a9
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/docs/types/test.ts
@@ -0,0 +1,98 @@
+/*
+* @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 logpdf = require( './index' );
+
+
+// TESTS //
+
+// The function returns a number...
+{
+ logpdf( 2, 4 ); // $ExpectType number
+ logpdf( 1, 8 ); // $ExpectType number
+}
+
+// The compiler throws an error if the function is provided values other than two numbers...
+{
+ logpdf( true, 6 ); // $ExpectError
+ logpdf( false, 4 ); // $ExpectError
+ logpdf( '5', 2 ); // $ExpectError
+ logpdf( [], 2 ); // $ExpectError
+ logpdf( {}, 4 ); // $ExpectError
+ logpdf( ( x: number ): number => x, 4 ); // $ExpectError
+
+ logpdf( 9, true ); // $ExpectError
+ logpdf( 9, false ); // $ExpectError
+ logpdf( 5, '5' ); // $ExpectError
+ logpdf( 8, [] ); // $ExpectError
+ logpdf( 9, {} ); // $ExpectError
+ logpdf( 8, ( x: number ): number => x ); // $ExpectError
+}
+
+// The compiler throws an error if the function is provided an unsupported number of arguments...
+{
+ logpdf(); // $ExpectError
+ logpdf( 2 ); // $ExpectError
+ logpdf( 2, 0, 4 ); // $ExpectError
+}
+
+// Attached to main export is a `factory` method which returns a function...
+{
+ logpdf.factory( 4 ); // $ExpectType Unary
+}
+
+// The `factory` method returns a function which returns a number...
+{
+ const fcn = logpdf.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 = logpdf.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 = logpdf.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 one number...
+{
+ logpdf.factory( true ); // $ExpectError
+ logpdf.factory( false ); // $ExpectError
+ logpdf.factory( '5' ); // $ExpectError
+ logpdf.factory( [] ); // $ExpectError
+ logpdf.factory( {} ); // $ExpectError
+ logpdf.factory( ( x: number ): number => x ); // $ExpectError
+}
+
+// The compiler throws an error if the `factory` method is provided an unsupported number of arguments...
+{
+ logpdf.factory(); // $ExpectError
+ logpdf.factory( 0, 4 ); // $ExpectError
+}
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/examples/c/Makefile b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/examples/c/Makefile
new file mode 100644
index 000000000000..c8f8e9a1517b
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/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/logpdf/examples/c/example.c b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/examples/c/example.c
new file mode 100644
index 000000000000..9fed4e03468d
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/examples/c/example.c
@@ -0,0 +1,41 @@
+/**
+* @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/logpdf.h"
+#include
+#include
+
+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_logpdf( x, sigma );
+ printf( "x: %lf, σ: %lf, ln(f(x;σ)): %lf\n", x, sigma, y );
+ }
+}
+
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/examples/index.js b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/examples/index.js
new file mode 100644
index 000000000000..5e02f3f01760
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/examples/index.js
@@ -0,0 +1,33 @@
+/**
+* @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 randu = require( '@stdlib/random/base/randu' );
+var logpdf = require( './../lib' );
+var i;
+var x;
+var y;
+var sigma;
+
+for ( i = 0; i < 25; i++ ) {
+ x = randu() * 3.0;
+ sigma = randu() * 3.0;
+ y = logpdf( x, sigma );
+ console.log( 'x: %lf, σ: %lf, ln(f(x;σ)): %lf', x, sigma, y );
+}
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/include.gypi b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/include.gypi
new file mode 100644
index 000000000000..bee8d41a2caf
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/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': [
+ '
+ */
+ function logpdf( x ) {
+ if ( isnan( x ) ) {
+ return NaN;
+ }
+ if ( x < 0.0 ) {
+ return NINF;
+ }
+ return C - lsigma - ( (x*x) / ( 2.0 * sigma2 ) );
+ }
+}
+
+
+// EXPORTS //
+
+module.exports = factory;
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/lib/index.js b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/lib/index.js
new file mode 100644
index 000000000000..bbed01cdffc7
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/lib/index.js
@@ -0,0 +1,54 @@
+/**
+* @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 logarithm of probability density function (PDF).
+*
+* @module @stdlib/stats/base/dists/halfnormal/logpdf
+*
+* @example
+* var logpdf = require( '@stdlib/stats/base/dists/halfnormal/logpdf' );
+*
+* var y = logpdf( 0.8, 1.0 );
+* // returns ~-0.546
+*
+* var mylogpdf = logpdf.factory( 1.0 );
+* y = mylogpdf( 0.8 );
+* // returns ~-0.546
+*
+* y = mylogpdf( 1.2 );
+* // returns ~-0.946
+*/
+
+// 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/logpdf/lib/main.js b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/lib/main.js
new file mode 100644
index 000000000000..9b6372097af9
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/lib/main.js
@@ -0,0 +1,95 @@
+/**
+* @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 ln = require( '@stdlib/math/base/special/ln' );
+var NINF = require( '@stdlib/constants/float64/ninf' );
+var LN2 = require( '@stdlib/constants/float64/ln-two' );
+var LNPI = require( '@stdlib/constants/float64/ln-pi' );
+
+
+// VARIABLES //
+
+// Constant: log(sqrt(2/pi)) = 0.5 * log(2/pi) = 0.5 * (ln(2) - ln(pi))
+var C = 0.5 * ( LN2 - LNPI );
+
+
+// MAIN //
+
+/**
+* Evaluates the logarithm of the probability density function (PDF) for a half-normal distribution with scale parameter `sigma`.
+*
+* @param {number} x - input value
+* @param {PositiveNumber} sigma - scale parameter
+* @returns {number} evaluated logarithm of PDF
+*
+* @example
+* var y = logpdf( 0.8, 1.0 );
+* // returns ~-0.546
+*
+* @example
+* var y = logpdf( 0.5, 1.0 );
+* // returns ~-0.351
+*
+* @example
+* var y = logpdf( 1.2, 2.0 );
+* // returns ~-1.099
+*
+* @example
+* var y = logpdf( -0.2, 1.0 );
+* // returns -Infinity
+*
+* @example
+* var y = logpdf( NaN, 1.0 );
+* // returns NaN
+*
+* @example
+* var y = logpdf( 0.0, NaN );
+* // returns NaN
+*
+* @example
+* // Negative scale parameter:
+* var y = logpdf( 2.0, -1.0 );
+* // returns NaN
+*
+* @example
+* var y = logpdf( 2.0, 0.0 );
+* // returns NaN
+*/
+function logpdf( x, sigma ) {
+ if (
+ isnan( x ) ||
+ isnan( sigma ) ||
+ sigma <= 0.0
+ ) {
+ return NaN;
+ }
+ if ( x < 0.0 ) {
+ return NINF;
+ }
+ return C - ln( sigma ) - ( (x*x) / ( 2.0 * (sigma*sigma) ) );
+}
+
+
+// EXPORTS //
+
+module.exports = logpdf;
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/lib/native.js b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/lib/native.js
new file mode 100644
index 000000000000..d3b462a51429
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/lib/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 addon = require( './../src/addon.node' );
+
+
+// MAIN //
+
+/**
+* Evaluates the logarithm of the probability density function (PDF) for a half-normal distribution with scale parameter `sigma`.
+*
+* @private
+* @param {number} x - input value
+* @param {PositiveNumber} sigma - scale parameter
+* @returns {number} evaluated logarithm of PDF
+*
+* @example
+* var y = logpdf( 0.8, 1.0 );
+* // returns ~-0.546
+*
+* @example
+* var y = logpdf( 0.5, 1.0 );
+* // returns ~-0.351
+*
+* @example
+* var y = logpdf( 1.2, 2.0 );
+* // returns ~-1.099
+*
+* @example
+* var y = logpdf( NaN, 1.0 );
+* // returns NaN
+*
+* @example
+* var y = logpdf( 0.0, NaN );
+* // returns NaN
+*
+* @example
+* // Negative scale parameter:
+* var y = logpdf( 2.0, -1.0 );
+* // returns NaN
+*/
+function logpdf( x, sigma ) {
+ return addon( x, sigma );
+}
+
+
+// EXPORTS //
+
+module.exports = logpdf;
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/manifest.json b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/manifest.json
new file mode 100644
index 000000000000..371b66f44298
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/manifest.json
@@ -0,0 +1,89 @@
+{
+ "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/main.c"
+ ],
+ "include": [
+ "./include"
+ ],
+ "libraries": [],
+ "libpath": [],
+ "dependencies": [
+ "@stdlib/math/base/napi/binary",
+ "@stdlib/math/base/assert/is-nan",
+ "@stdlib/math/base/special/ln",
+ "@stdlib/constants/float64/ninf",
+ "@stdlib/constants/float64/ln-two",
+ "@stdlib/constants/float64/ln-pi"
+ ]
+ },
+ {
+ "task": "benchmark",
+ "wasm": false,
+ "src": [
+ "./src/main.c"
+ ],
+ "include": [
+ "./include"
+ ],
+ "libraries": [],
+ "libpath": [],
+ "dependencies": [
+ "@stdlib/constants/float64/eps",
+ "@stdlib/math/base/assert/is-nan",
+ "@stdlib/math/base/special/ln",
+ "@stdlib/constants/float64/ninf",
+ "@stdlib/constants/float64/ln-two",
+ "@stdlib/constants/float64/ln-pi"
+ ]
+ },
+ {
+ "task": "examples",
+ "wasm": false,
+ "src": [
+ "./src/main.c"
+ ],
+ "include": [
+ "./include"
+ ],
+ "libraries": [],
+ "libpath": [],
+ "dependencies": [
+ "@stdlib/math/base/assert/is-nan",
+ "@stdlib/math/base/special/ln",
+ "@stdlib/constants/float64/ninf",
+ "@stdlib/constants/float64/ln-two",
+ "@stdlib/constants/float64/ln-pi"
+ ]
+ }
+ ]
+}
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/package.json b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/package.json
new file mode 100644
index 000000000000..2f272468cae7
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/package.json
@@ -0,0 +1,70 @@
+{
+ "name": "@stdlib/stats/base/dists/halfnormal/logpdf",
+ "version": "0.0.0",
+ "description": "Half-normal distribution logarithm of 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",
+ "probability",
+ "pdf",
+ "log",
+ "logarithm",
+ "halfnormal",
+ "half-normal",
+ "univariate",
+ "continuous"
+ ]
+}
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/src/Makefile b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/src/Makefile
new file mode 100644
index 000000000000..2caf905cedbe
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/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/logpdf/src/addon.c b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/src/addon.c
new file mode 100644
index 000000000000..36032875f1e1
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/src/addon.c
@@ -0,0 +1,23 @@
+/**
+* @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/logpdf.h"
+#include "stdlib/math/base/napi/binary.h"
+
+// cppcheck-suppress shadowFunction
+STDLIB_MATH_BASE_NAPI_MODULE_DD_D( stdlib_base_dists_halfnormal_logpdf )
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/src/main.c b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/src/main.c
new file mode 100644
index 000000000000..c059080d2ad0
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/src/main.c
@@ -0,0 +1,52 @@
+/**
+* @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/logpdf.h"
+#include "stdlib/math/base/assert/is_nan.h"
+#include "stdlib/math/base/special/ln.h"
+#include "stdlib/constants/float64/ninf.h"
+#include "stdlib/constants/float64/ln_two.h"
+#include "stdlib/constants/float64/ln_pi.h"
+
+// log(sqrt(2/pi)) = 0.5 * log(2/pi) = 0.5 * (ln(2) - ln(pi))
+static const double C = 0.5 * ( STDLIB_CONSTANT_FLOAT64_LN2 - STDLIB_CONSTANT_FLOAT64_LN_PI );
+
+/**
+* Evaluates the logarithm of the probability density function (PDF) for a half-normal distribution with scale parameter `sigma`.
+*
+* @param x input value
+* @param sigma scale parameter
+* @return evaluated logarithm of PDF
+*
+* @example
+* double y = stdlib_base_dists_halfnormal_logpdf( 0.8, 1.0 );
+* // returns ~-0.546
+*/
+double stdlib_base_dists_halfnormal_logpdf( const double x, const double sigma ) {
+ 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 STDLIB_CONSTANT_FLOAT64_NINF;
+ }
+ return C - stdlib_base_ln( sigma ) - ( (x*x) / ( 2.0 * (sigma*sigma) ) );
+}
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/test/fixtures/julia/REQUIRE b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/test/fixtures/julia/REQUIRE
new file mode 100644
index 000000000000..98be20b58ed3
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/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/logpdf/test/fixtures/julia/data.json b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/test/fixtures/julia/data.json
new file mode 100644
index 000000000000..19b1962876b9
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/test/fixtures/julia/data.json
@@ -0,0 +1 @@
+{"sigma":[2.604571695435689,7.499267153061186,3.348443855723051,1.954656979562216,3.4049481714068417,6.694631267188975,1.897307581920854,7.221912944090477,4.428811597768087,2.4767418429270482,6.941608679942151,5.864079750113497,9.744395766910703,9.272117265419165,9.988829036928026,6.779122786581012,0.7344609031856131,6.848342644396962,8.018330605129464,5.211868729540758,2.3049364727134636,3.8315010098974422,3.46800097207554,1.5599123588514552,6.606717962977018,7.410696875212648,6.874823897663963,3.221496034765312,6.235041810997416,1.3279597463672854,9.44146426673753,8.177461380129431,8.927627725609304,4.406701773566557,2.852317172153832,7.194955481350123,4.992607310115855,2.1282797618395977,3.483472273063902,6.627323443545885,6.6103097072837835,0.061096215826882405,7.412790779606869,0.9466556204581333,4.571859970254888,1.931551192703298,3.0050261601448183,3.3949380738891675,3.977296226018817,2.700967519855426,5.126833560160161,5.616177103419712,1.8756315123769007,3.3196801406426726,6.725542374817428,4.329955792526475,0.4250911560354642,9.461735987270043,0.6586927594496961,7.608269203215405,4.714445084719174,7.717980819408167,6.611644656967205,2.141484432321785,7.452733887330439,9.079982729334489,4.947811285888593,7.674682718699137,1.5793640726621627,5.885322199835191,9.199118278524676,5.734807081684206,7.366268858939776,0.03081687237524222,7.30137974782418,6.2731988226528905,1.9399025338398501,8.533172406966006,7.281618821026958,8.450155804925846,9.442668127724156,8.905360482641246,7.19802113263418,1.9995797415912842,3.1276311973458837,2.9685041501187936,9.983864537874025,1.5435189154177198,9.648277243231119,2.126066458700252,4.5466723024373765,5.914609833065201,0.7522464699638964,0.1699111408636922,0.2974724608114432,6.83637731242278,7.466071533354251,3.9337878013432395,7.197819493259593,5.882080876108651,2.3433828403210475,4.208632602100355,2.402290614235584,3.631925025637713,1.1876197549565193,5.911275813358032,1.8573952682854777,6.800769875989423,7.8763574742869755,8.34301823558079,3.779134698451866,0.9113517969178353,5.827640899773055,9.978794133832844,9.316042705766776,6.41172758094572,2.1136190041417646,6.80329543771399,0.5228328044946118,9.342465842369826,0.6899510144698184,2.401357651425038,6.569897634892486,6.5597841778007755,3.5123842971085315,5.454422499207389,2.8469424556343714,3.1511666712568056,7.042468052019869,7.701449272841541,1.9848872374526205,7.249009151223746,3.744987731234244,4.447337284058534,6.079028552843232,5.478180230282485,3.497906073915995,2.5695518987215027,5.15774288347941,8.614642914974516,6.604485498547804,4.962010431240841,4.384220585238067,1.6073973936985708,0.30677632383480535,7.599702224033368,1.3507874746320037,0.033302282516709525,7.862568181804671,2.009560882443947,4.059844753881587,0.5645662015751185,3.0274440109350076,9.638700752083727,4.031019765960614,6.141440401938864,1.761194274613146,2.5594009882793567,6.11194348649394,1.43195553324583,8.493334961321331,3.759331078600634,9.808853017764541,1.3213352034772674,6.503743567682694,1.8972571702963592,2.3857959629167222,7.921794655507118,1.9954696019464824,2.218004346754544,8.469211637539878,3.9062266063723614,5.248394114315007,9.184245836353762,9.203937128502,5.599345253623577,6.779095435692776,1.826583095795291,7.015873953614421,1.7864311963901647,5.011358382009109,0.6470971885279242,9.195234367419598,0.7874694428933426,5.416660805405165,5.198403368016576,9.253241653474346,3.24843709611917,5.349511246036897,2.1790328463953346,8.890143031721442,5.307417725023211,1.5329275582299007,6.234025407360917,1.6612981135523863,6.121416986356117,2.5731878015843943,0.9888453932854835,2.6704393130399664,3.5801849350579227,6.207369589686255,5.714817552781277,2.2915938865522243,6.707507757581007,1.1259067150458457,3.697549584157075,7.936520690034032,5.196305439455045,8.321035149306683,0.590242173399913,1.2907685122160717,4.600849303622966,2.673649881074213,5.960561090224231,1.2512496898840009,6.864428249326485,8.468752755121008,5.61103837397558,7.918832904075375,9.634412884912592,1.406626383340882,7.784472413479309,5.336413218604309,0.9408615136975984,9.122866631139354,1.767105963946849,8.096074889235728,5.407638630445767,0.3247329632531992,5.481060696205128,0.5014312420424416,7.940886248580753,3.435478003911807,5.485914820603188,3.2142821346641623,1.5333586509842834,7.222083783969284,6.0174548350685795,6.63198992825163,4.781160821102412,8.256571226901285,7.457094782134071,2.772301678503072,3.7078513559704174,5.6346962699407355,6.128341196103938,9.010114712113722,2.2598714449919752,0.1889602747176944,7.096189092815654,6.868846777979782,0.4209953025342872,9.866126063715146,8.14316253981656,2.9845627968962707,5.097748958896519,6.261496804523221,7.137653829376132,9.886873576164643,5.965277669151455,0.07011972662105403,4.063791807813283,6.1611190224566235,1.0959707873213287,4.576953479256925,5.90606945853529,9.654672962156841,9.688671254962339,9.710506569297284,3.1853088830387764,4.2904458012890725,9.971288891349083,6.6550883836239265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diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/test/fixtures/julia/runner.jl b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/test/fixtures/julia/runner.jl
new file mode 100644
index 000000000000..c6ef116ff9ca
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/test/fixtures/julia/runner.jl
@@ -0,0 +1,74 @@
+#!/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.
+
+import Distributions: logpdf, Normal, Truncated
+import JSON
+
+"""
+ gen( x, sigma, name )
+
+Generate fixture data and write to file.
+
+# Arguments
+
+* `x`: input value
+* `sigma`: scale parameter
+* `name::AbstractString`: output filename
+
+# Examples
+
+``` julia
+julia> x = rand( 1000 ) .* 10.0;
+julia> sigma = rand( 1000 ) .* 10.0;
+julia> gen( x, sigma, "data.json" );
+```
+"""
+function gen( x, sigma, name )
+ z = Array{Float64}( undef, length(x) );
+ for i in eachindex(x)
+ d = Truncated( Normal( 0.0, sigma[i] ), 0.0, Inf );
+ z[ i ] = logpdf( d, x[i] );
+ end
+
+ # Store data to be written to file as a collection:
+ data = Dict([
+ ("x", x),
+ ("sigma", sigma),
+ ("expected", z)
+ ]);
+
+ # Based on the script directory, create an output filepath:
+ filepath = joinpath( dir, name );
+
+ # Write the data to the output filepath as JSON:
+ outfile = open( filepath, "w" );
+ write( outfile, JSON.json(data) );
+ write( outfile, "\n" );
+ close( outfile );
+end
+
+# Get the filename:
+file = @__FILE__;
+
+# Extract the directory in which this file resides:
+dir = dirname( file );
+
+# Generate a single fixture file:
+x = rand( 10 ) .* 10.0;
+sigma = rand( 1000 ) .* 10.0 .+ 1e-80; # Ensure sigma is positive
+gen( x, sigma, "data.json" );
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/test/test.factory.js b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/test/test.factory.js
new file mode 100644
index 000000000000..65a64175e49c
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/test/test.factory.js
@@ -0,0 +1,118 @@
+/**
+* @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 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 logpdf = factory( 1.0 );
+ t.strictEqual( typeof logpdf, 'function', 'returns expected value' );
+ t.end();
+});
+
+tape( 'if provided `NaN` for `sigma`, the created function returns `NaN`', function test( t ) {
+ var logpdf;
+ var y;
+
+ logpdf = factory( NaN );
+ y = logpdf( 0.0 );
+ t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+ t.end();
+});
+
+tape( 'if provided `sigma <= 0`, the created function always returns `NaN`', function test( t ) {
+ var logpdf;
+ var y;
+
+ logpdf = factory( -1.0 );
+
+ y = logpdf( 2.0 );
+ t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+ y = logpdf( 0.0 );
+ t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+ logpdf = factory( 0.0 );
+
+ y = logpdf( 2.0 );
+ t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+ y = logpdf( 0.0 );
+ t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+ t.end();
+});
+
+tape( 'the created function returns `-Infinity` if provided `x < 0`', function test( t ) {
+ var logpdf;
+ var y;
+
+ logpdf = factory( 1.0 );
+ y = logpdf( -1.0 );
+ t.strictEqual( y, NINF, 'returns expected value' );
+
+ t.end();
+});
+
+tape( 'the created function evaluates the logpdf', function test( t ) {
+ var logpdf;
+ var delta;
+ var tol;
+ var x;
+ var y;
+ var i;
+
+ x = data.x;
+ for ( i = 0; i < x.length; i++ ) {
+ logpdf = factory( data.sigma[i] );
+ y = logpdf( x[i] );
+ if ( data.expected[i] !== null ) {
+ if ( y === data.expected[i] ) {
+ t.strictEqual( y, data.expected[i], 'x: '+x[i]+', sigma: '+data.sigma[i]+', y: '+y+', expected: '+data.expected[i] );
+ } else {
+ delta = abs( y - data.expected[ i ] );
+ tol = 40.0 * EPS * abs( data.expected[ i ] );
+ t.ok( delta <= tol, 'within tolerance. x: '+x[ i ]+'. sigma: '+data.sigma[i]+'. y: '+y+'. E: '+data.expected[ i ]+'. Δ: '+delta+'. tol: '+tol+'.' );
+ }
+ }
+ }
+ t.end();
+});
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/test/test.js b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/test/test.js
new file mode 100644
index 000000000000..c8fb79a7c82a
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/test/test.js
@@ -0,0 +1,38 @@
+/**
+* @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 logpdf = require( './../lib' );
+
+
+// TESTS //
+
+tape( 'main export is a function', function test( t ) {
+ t.ok( true, __filename );
+ t.strictEqual( typeof logpdf, 'function', 'main export is a function' );
+ t.end();
+});
+
+tape( 'attached to the main export is a factory method for generating `logpdf` functions', function test( t ) {
+ t.strictEqual( typeof logpdf.factory, 'function', 'exports a factory method' );
+ t.end();
+});
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/test/test.logpdf.js b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/test/test.logpdf.js
new file mode 100644
index 000000000000..901ad59dfd60
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/test/test.logpdf.js
@@ -0,0 +1,102 @@
+/**
+* @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 NINF = require( '@stdlib/constants/float64/ninf' );
+var EPS = require( '@stdlib/constants/float64/eps' );
+var logpdf = require( './../lib/main.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 logpdf, 'function', 'main export is a function' );
+ t.end();
+});
+
+tape( 'if provided `NaN` for any parameter, the function returns `NaN`', function test( t ) {
+ var y = logpdf( NaN, 1.0 );
+ t.strictEqual( isnan( y ), true, 'returns expected value' );
+ y = logpdf( 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 = logpdf( 2.0, -1.0 );
+ t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+ y = logpdf( 0.0, -1.0 );
+ t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+ y = logpdf( 2.0, 0.0 );
+ t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+ y = logpdf( 0.0, 0.0 );
+ t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+ t.end();
+});
+
+tape( 'if provided `x < 0`, the function returns `-Infinity`', function test( t ) {
+ var y = logpdf( -1.0, 1.0 );
+ t.strictEqual( y, NINF, 'returns expected value' );
+ t.end();
+});
+
+tape( 'the function evaluates the logpdf', function test( t ) {
+ var expected;
+ var delta;
+ var sigma;
+ var tol;
+ var x;
+ var y;
+ var i;
+
+ x = data.x;
+ sigma = data.sigma;
+ expected = data.expected;
+
+ for ( i = 0; i < x.length; i++ ) {
+ y = logpdf( x[i], sigma[i] );
+ if ( expected[i] !== null ) {
+ 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/logpdf/test/test.native.js b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/test/test.native.js
new file mode 100644
index 000000000000..0e12b55d53e5
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/logpdf/test/test.native.js
@@ -0,0 +1,111 @@
+/**
+* @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 NINF = require( '@stdlib/constants/float64/ninf' );
+var EPS = require( '@stdlib/constants/float64/eps' );
+
+
+// FIXTURES //
+
+var data = require( './fixtures/julia/data.json' );
+
+
+// VARIABLES //
+
+var logpdf = tryRequire( resolve( __dirname, './../lib/native.js' ) );
+var opts = {
+ 'skip': ( logpdf instanceof Error )
+};
+
+
+// TESTS //
+
+tape( 'main export is a function', opts, function test( t ) {
+ t.ok( true, __filename );
+ t.strictEqual( typeof logpdf, '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 = logpdf( NaN, 1.0 );
+ t.strictEqual( isnan( y ), true, 'returns expected value' );
+ y = logpdf( 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 = logpdf( 2.0, -1.0 );
+ t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+ y = logpdf( 0.0, -1.0 );
+ t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+ y = logpdf( 2.0, 0.0 );
+ t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+ y = logpdf( 0.0, 0.0 );
+ t.strictEqual( isnan( y ), true, 'returns expected value' );
+
+ t.end();
+});
+
+tape( 'if provided `x < 0`, the function returns `-Infinity`', opts, function test( t ) {
+ var y = logpdf( -1.0, 1.0 );
+ t.strictEqual( y, NINF, 'returns expected value' );
+ t.end();
+});
+
+tape( 'the function evaluates the logpdf', opts, function test( t ) {
+ var expected;
+ var delta;
+ var sigma;
+ var tol;
+ var x;
+ var y;
+ var i;
+
+ x = data.x;
+ sigma = data.sigma;
+ expected = data.expected;
+
+ for ( i = 0; i < x.length; i++ ) {
+ y = logpdf( x[i], sigma[i] );
+ if ( expected[i] !== null ) {
+ 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();
+});