diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/README.md b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/README.md
new file mode 100755
index 000000000000..13e597f368ad
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/README.md
@@ -0,0 +1,229 @@
+
+
+# Standard Deviation
+
+> [Half-normal][half-normal-distribution] distribution [standard deviation][standard-deviation].
+
+
+
+
+
+The [standard deviation][standard-deviation] for a [half-normal][half-normal-distribution] random variable is
+
+
+
+```math
+\sigma\sqrt{1-\frac{2}{\pi}}
+```
+
+
+
+where `σ > 0` is the scale parameter.
+
+
+
+
+
+
+
+
+
+## Usage
+
+```javascript
+var stdev = require( '@stdlib/stats/base/dists/halfnormal/stdev' );
+```
+
+#### stdev( sigma )
+
+Returns the [standard deviation][standard-deviation] of a [half-normal][half-normal-distribution] distribution with scale `sigma`.
+
+```javascript
+var y = stdev( 9.0 );
+// returns 5.425292474901783
+
+y = stdev( 3.5 );
+// returns 2.109835962461804
+```
+
+If provided `sigma < 0`, the function returns `NaN`.
+
+```javascript
+var y = stdev( -1.0 );
+// returns NaN
+```
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+## Examples
+
+
+
+```javascript
+var uniform = require( '@stdlib/random/array/uniform' );
+var logEachMap = require( '@stdlib/console/log-each-map' );
+var stdev = require( '@stdlib/stats/base/dists/halfnormal/stdev' );
+
+var opts = {
+ 'dtype': 'float64'
+};
+var sigma = uniform( 10, 0.1, 20.0, opts );
+
+logEachMap( 'σ: %0.4f, SD(X;σ): %0.4f', sigma, stdev );
+```
+
+
+
+
+
+
+
+* * *
+
+
+
+## C APIs
+
+
+
+
+
+
+
+
+
+
+
+### Usage
+
+```c
+#include "stdlib/stats/base/dists/halfnormal/stdev.h"
+```
+
+### stdlib_base_dists_halfnormal_stdev( sigma )
+
+Returns the [standard deviation][standard-deviation] of a [half-normal][half-normal-distribution] distribution with scale `sigma`.
+
+```c
+double out = stdlib_base_dists_halfnormal_stdev( 9.0 );
+// returns 5.425292474901783
+```
+
+The function accepts the following arguments:
+
+- **sigma**: `[in] double` scale parameter.
+
+```c
+double stdlib_base_dists_halfnormal_stdev( const double sigma );
+```
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+### Examples
+
+```c
+#include "stdlib/stats/base/dists/halfnormal/stdev.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 y;
+ int i;
+
+ for ( i = 0; i < 25; i++ ) {
+ sigma = random_uniform( 0.1, 20.0 );
+ y = stdlib_base_dists_halfnormal_stdev( sigma );
+ printf( "σ: %lf, SD(X;σ): %lf\n", sigma, y );
+ }
+}
+```
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+[half-normal-distribution]: https://en.wikipedia.org/wiki/Half-normal_distribution
+
+[standard-deviation]: https://en.wikipedia.org/wiki/Standard_deviation
+
+
+
+
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/benchmark/benchmark.js b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/benchmark/benchmark.js
new file mode 100755
index 000000000000..72191006b613
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/benchmark/benchmark.js
@@ -0,0 +1,60 @@
+/**
+* @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 stdev = require( './../lib' );
+
+
+// MAIN //
+
+bench( pkg, function benchmark( b ) {
+ var sigma;
+ var len;
+ var y;
+ var i;
+
+ len = 100;
+ sigma = new Float64Array( len );
+ for ( i = 0; i < len; i++ ) {
+ sigma[ i ] = uniform( EPS, 20.0 );
+ }
+
+ b.tic();
+ for ( i = 0; i < b.iterations; i++ ) {
+ y = stdev( 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/stdev/benchmark/benchmark.native.js b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/benchmark/benchmark.native.js
new file mode 100755
index 000000000000..6f84331a1908
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/benchmark/benchmark.native.js
@@ -0,0 +1,69 @@
+/**
+* @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 uniform = require( '@stdlib/random/base/uniform' );
+var EPS = require( '@stdlib/constants/float64/eps' );
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+var tryRequire = require( '@stdlib/utils/try-require' );
+var format = require( '@stdlib/string/format' );
+var pkg = require( './../package.json' ).name;
+
+
+// VARIABLES //
+
+var stdev = tryRequire( resolve( __dirname, './../lib/native.js' ) );
+var opts = {
+ 'skip': ( stdev instanceof Error )
+};
+
+
+// MAIN //
+
+bench( format( '%s::native', pkg ), opts, function benchmark(b) {
+ var sigma;
+ var len;
+ var y;
+ var i;
+
+ len = 100;
+ sigma = new Float64Array( len );
+ for ( i = 0; i < len; i++ ) {
+ sigma[ i ] = uniform( EPS, 20.0 );
+ }
+
+ b.tic();
+ for ( i = 0; i < b.iterations; i++ ) {
+ y = stdev( 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/stdev/benchmark/c/Makefile b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/benchmark/c/Makefile
new file mode 100755
index 000000000000..979768abbcec
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/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/stdev/benchmark/c/benchmark.c b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/benchmark/c/benchmark.c
new file mode 100755
index 000000000000..7c2e1b1250f3
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/benchmark/c/benchmark.c
@@ -0,0 +1,140 @@
+/**
+* @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/stdev.h"
+#include "stdlib/constants/float64/eps.h"
+#include
+#include
+#include
+#include
+#include
+
+#define NAME "halfnormal-stdev"
+#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 );
+ printf( "# total %d\n", total );
+ printf( "# pass %d\n", passing );
+ printf( "#\n" );
+ printf( "# ok\n" );
+}
+
+/**
+* Prints benchmark 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 y;
+ double t;
+ int i;
+
+ for ( i = 0; i < 100; i++ ) {
+ sigma[ i ] = random_uniform( STDLIB_CONSTANT_FLOAT64_EPS, 20.0 );
+ }
+
+ t = tic();
+ for ( i = 0; i < ITERATIONS; i++ ) {
+ y = stdlib_base_dists_halfnormal_stdev( 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/stdev/binding.gyp b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/binding.gyp
new file mode 100755
index 000000000000..0d6508a12e99
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/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/stdev/docs/repl.txt b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/docs/repl.txt
new file mode 100755
index 000000000000..7c3b6aa97b69
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/docs/repl.txt
@@ -0,0 +1,26 @@
+{{alias}}( σ )
+ Returns the standard deviation of a half-normal distribution.
+
+ If provided `NaN` as any argument, the function returns `NaN`.
+
+ If provided `σ < 0`, the function returns `NaN`.
+
+ Parameters
+ ----------
+ σ: number
+ Scale parameter.
+
+ Returns
+ -------
+ out: number
+ Standard deviation.
+
+ Examples
+ --------
+ > var v = {{alias}}( 9.0 )
+ ~5.425292474901783
+ > v = {{alias}}( 2.0 )
+ ~1.2056205499781738
+
+ See Also
+ --------
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/docs/types/index.d.ts b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/docs/types/index.d.ts
new file mode 100755
index 000000000000..ee2624cf7454
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/docs/types/index.d.ts
@@ -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.
+*/
+
+// TypeScript Version: 4.1
+
+/**
+* Returns the standard deviation of a half-normal distribution.
+*
+* ## Notes
+*
+* - If provided `σ < 0`, the function returns `NaN`.
+*
+* @param sigma - scale parameter
+* @returns standard deviation
+*
+* @example
+* var v = stdev( 9.0 );
+* // returns ~5.425292474901783
+*
+* @example
+* var v = stdev( 2.0 );
+* // returns ~1.2056205499781738
+*
+* @example
+* var v = stdev( -0.2 );
+* // returns NaN
+*
+* @example
+* var v = stdev( NaN );
+* // returns NaN
+*/
+declare function stdev( sigma: number ): number;
+
+
+// EXPORTS //
+
+export = stdev;
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/docs/types/test.ts b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/docs/types/test.ts
new file mode 100755
index 000000000000..3ba2b7d34cbf
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/docs/types/test.ts
@@ -0,0 +1,44 @@
+/*
+* @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 stdev = require( './index' );
+
+
+// TESTS //
+
+// The function returns a number...
+{
+ stdev( 0.3 ); // $ExpectType number
+}
+
+// The compiler throws an error if the function is provided a value other than a number...
+{
+ stdev( true ); // $ExpectError
+ stdev( false ); // $ExpectError
+ stdev( null ); // $ExpectError
+ stdev( undefined ); // $ExpectError
+ stdev( '5' ); // $ExpectError
+ stdev( [] ); // $ExpectError
+ stdev( {} ); // $ExpectError
+ stdev( ( x: number ): number => x ); // $ExpectError
+}
+
+// The compiler throws an error if the function is provided insufficient arguments...
+{
+ stdev(); // $ExpectError
+}
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/examples/c/Makefile b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/examples/c/Makefile
new file mode 100755
index 000000000000..c8f8e9a1517b
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/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/stdev/examples/c/example.c b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/examples/c/example.c
new file mode 100755
index 000000000000..8ca35915d7c8
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/examples/c/example.c
@@ -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.
+*/
+
+#include "stdlib/stats/base/dists/halfnormal/stdev.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 y;
+ int i;
+
+ for ( i = 0; i < 25; i++ ) {
+ sigma = random_uniform( 0.1, 10.0 );
+ y = stdlib_base_dists_halfnormal_stdev( sigma );
+ printf( "σ: %lf, SD(X;σ): %lf\n", sigma, y );
+ }
+}
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/examples/index.js b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/examples/index.js
new file mode 100755
index 000000000000..9f5c45333a19
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/examples/index.js
@@ -0,0 +1,30 @@
+/**
+* @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 stdev = require( './../lib' );
+
+var opts = {
+ 'dtype': 'float64'
+};
+var sigma = uniform( 10, 0.1, 20.0, opts );
+
+logEachMap( 'σ: %0.4f, SD(X;σ): %0.4f', sigma, stdev );
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/include.gypi b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/include.gypi
new file mode 100755
index 000000000000..bee8d41a2caf
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/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': [
+ '=0.10.0",
+ "npm": ">2.7.0"
+ },
+ "os": [
+ "aix",
+ "darwin",
+ "freebsd",
+ "linux",
+ "macos",
+ "openbsd",
+ "sunos",
+ "win32",
+ "windows"
+ ],
+ "keywords": [
+ "stdlib",
+ "stdmath",
+ "statistics",
+ "stats",
+ "distribution",
+ "dist",
+ "gaussian",
+ "halfnormal",
+ "continuous",
+ "standard",
+ "deviation",
+ "stdev",
+ "std",
+ "spread",
+ "dispersion",
+ "univariate"
+ ]
+}
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/src/Makefile b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/src/Makefile
new file mode 100755
index 000000000000..2caf905cedbe
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/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/stdev/src/addon.c b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/src/addon.c
new file mode 100755
index 000000000000..25bad3505354
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/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/stdev.h"
+#include "stdlib/math/base/napi/unary.h"
+
+STDLIB_MATH_BASE_NAPI_MODULE_D_D( stdlib_base_dists_halfnormal_stdev )
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/src/main.c b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/src/main.c
new file mode 100755
index 000000000000..4b89a88f11e2
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/src/main.c
@@ -0,0 +1,42 @@
+/**
+* @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/stdev.h"
+#include "stdlib/math/base/assert/is_nan.h"
+
+static const double SQRT1M2PI = 0.6028102749890869; // sqrt(1 - 2/pi)
+
+/**
+* Returns the standard deviation of a half-normal distribution.
+*
+* @param sigma scale parameter
+* @return standard deviation
+*
+* @example
+* double v = stdlib_base_dists_halfnormal_stdev( 2.0 );
+* // returns ~1.2056
+*/
+double stdlib_base_dists_halfnormal_stdev( const double sigma ) {
+ if (
+ stdlib_base_is_nan( sigma ) ||
+ sigma < 0.0
+ ) {
+ return 0.0/0.0; // NaN
+ }
+ return sigma * SQRT1M2PI;
+}
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/test/fixtures/julia/REQUIRE b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/test/fixtures/julia/REQUIRE
new file mode 100755
index 000000000000..98be20b58ed3
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/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/stdev/test/fixtures/julia/data.json b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/test/fixtures/julia/data.json
new file mode 100755
index 000000000000..b6be035fce04
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/test/fixtures/julia/data.json
@@ -0,0 +1,32 @@
+{
+ "sigma": [
+ 18.85019126246455, 6.815489890726541, 2.4528028962506747, 5.52828434540982,
+ 11.76480827117304, 12.216327775083297, 18.95871415268353, 8.437297087195631,
+ 19.557257165385046, 11.362719384741425, 11.013395500405874, 16.951338263629626,
+ 9.047073335857913, 2.577081059735365, 11.83717172838757, 14.785690111153304,
+ 16.56933028428779, 20.952586004767657, 6.7358177234078624, 16.320670601385043,
+ 5.82279301905089, 21.333430683837992, 10.500092704309195, 10.170477298914145,
+ 17.24697141680967, 8.05342552516345, 12.44468319842698, 20.444669282818595,
+ 9.899379365307912, 20.945698578359757, 10.09022316621611, 5.8542885467509524,
+ 13.399915292407563, 18.870914589663215, 8.68669540352445, 20.746729831193605,
+ 6.68085204116103, 12.262974326022668, 9.25157045118463, 20.189685268578533,
+ 11.716974480444138, 5.362441952744555, 9.925273362418071, 12.96088212770181,
+ 7.495070839707887, 10.643342368188186, 20.21575020229341, 21.76937424634205,
+ 6.085479875231921, 7.970382058450792
+ ],
+ "expected": [
+ 11.363088978523138, 4.108447335214208, 1.478574788382898, 3.332506606474358,
+ 7.091947309139704, 7.364127905454782, 11.428507691818652, 5.086089377297021,
+ 11.789315569898049, 6.849563996939807, 6.638987970163237, 10.218440880131606,
+ 5.453668765434944, 1.553490942288243, 7.135568744682357, 8.912965921807746,
+ 9.988162545056529, 12.630434131266485, 4.060420134123859, 9.838267933227224,
+ 3.510039461018602, 12.860011216985004, 6.329563770495531, 6.130868217328701,
+ 10.396651582495960, 4.854687655427910, 7.501782900995837, 12.324256712436815,
+ 5.967447597422555, 12.626282319859572, 6.082490201527988, 3.529025288732404,
+ 8.077606622246673, 11.375581213090454, 5.236429244945011, 12.506341914666109,
+ 4.027286256093683, 7.392246925653837, 5.576941727759518, 12.170549728694942,
+ 7.063112608596645, 3.232535108146961, 5.983056764941097, 7.812952919501070,
+ 4.518105713946998, 6.415916139770520, 12.186261938555180, 13.122802475777798,
+ 3.668389797029108, 4.804628200422807
+ ]
+}
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/test/fixtures/julia/runner.jl b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/test/fixtures/julia/runner.jl
new file mode 100755
index 000000000000..2dcb6faa7808
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/test/fixtures/julia/runner.jl
@@ -0,0 +1,68 @@
+#!/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: var, HalfNormal
+import JSON
+
+"""
+ gen( sigma, name )
+
+Generate fixture data and write to file.
+
+# Arguments
+
+* `sigma`: scale parameter
+* `name::AbstractString`: output filename
+
+# Examples
+
+``` julia
+julia> sigma = rand( 1000 );
+julia> gen( sigma, \"data.json\" );
+```
+"""
+# Get the filename:
+file = @__FILE__
+
+# Extract the directory in which this file resides:
+dir = dirname(file)
+
+function gen( sigma, name )
+ z = Array{Float64}( undef, length(sigma) )
+ for i in eachindex(sigma)
+ z[i] = sqrt( var( HalfNormal( sigma[i] ) ) )
+ end
+ # Store data to be written to file as a collection:
+ data = Dict([
+ ("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:
+ open(filepath, "w") do outfile
+ write(outfile, JSON.json(data))
+ write(outfile, "\n")
+ end
+end
+
+# Generate fixtures:
+sigma = ( rand(50) .* 20.0 ) .+ 2.0
+gen(sigma, "data.json")
diff --git a/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/test/test.js b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/test/test.js
new file mode 100755
index 000000000000..6329a2cf8ffc
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/test/test.js
@@ -0,0 +1,83 @@
+/**
+* @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 stdev = 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 stdev, 'function', 'main export is a function' );
+ t.end();
+});
+
+tape( 'if provided `NaN` for `sigma`, the function returns `NaN`', function test( t ) {
+ var sigma = stdev( NaN );
+ t.strictEqual( isnan( sigma ), true, 'returns expected value' );
+ t.end();
+});
+
+tape( 'if provided a scale `sigma` that is not a nonnegative number, the function returns `NaN`', function test( t ) {
+ var sigma;
+
+ sigma = stdev( -1.0 );
+ t.strictEqual( isnan( sigma ), true, 'returns expected value' );
+
+ sigma = stdev( NINF );
+ t.strictEqual( isnan( sigma ), true, 'returns expected value' );
+
+ t.end();
+});
+
+tape( 'the function returns the standard deviation of a half-normal distribution', function test( t ) {
+ var expected;
+ var delta;
+ var sigma;
+ var tol;
+ var i;
+ var y;
+
+ expected = data.expected;
+ sigma = data.sigma;
+ for ( i = 0; i < expected.length; i++ ) {
+ y = stdev( sigma[i] );
+ if ( y === expected[i] ) {
+ t.strictEqual( y, expected[i], ', sigma: '+sigma[i]+', y: '+y+', expected: '+expected[i] );
+ } else {
+ delta = abs( y - expected[ i ] );
+ tol = 1.5 * EPS * abs( expected[ i ] );
+ t.ok( delta <= tol, 'within tolerance. 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/stdev/test/test.native.js b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/test/test.native.js
new file mode 100755
index 000000000000..8c007622213b
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/base/dists/halfnormal/stdev/test/test.native.js
@@ -0,0 +1,92 @@
+/**
+* @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 isnan = require( '@stdlib/math/base/assert/is-nan' );
+var tryRequire = require( '@stdlib/utils/try-require' );
+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 stdev = tryRequire( resolve( __dirname, './../lib/native.js' ) );
+var opts = {
+ 'skip': ( stdev instanceof Error )
+};
+
+
+// TESTS //
+
+tape( 'main export is a function', opts, function test( t ) {
+ t.ok( true, __filename );
+ t.strictEqual( typeof stdev, 'function', 'main export is a function' );
+ t.end();
+});
+
+tape( 'if provided `NaN` for `sigma`, the function returns `NaN`', opts, function test( t ) {
+ var sigma = stdev( NaN );
+ t.strictEqual( isnan( sigma ), true, 'returns expected value' );
+ t.end();
+});
+
+tape( 'if provided a scale `sigma` that is not a nonnegative number, the function returns `NaN`', opts, function test( t ) {
+ var sigma;
+
+ sigma = stdev( -1.0 );
+ t.strictEqual( isnan( sigma ), true, 'returns expected value' );
+
+ sigma = stdev( NINF );
+ t.strictEqual( isnan( sigma ), true, 'returns expected value' );
+
+ t.end();
+});
+
+tape( 'the function returns the standard deviation of a half-normal distribution', opts, function test( t ) {
+ var expected;
+ var delta;
+ var sigma;
+ var tol;
+ var i;
+ var y;
+
+ expected = data.expected;
+ sigma = data.sigma;
+ for ( i = 0; i < expected.length; i++ ) {
+ y = stdev( sigma[i] );
+ if ( y === expected[i] ) {
+ t.strictEqual( y, expected[i], ', sigma: '+sigma[i]+', y: '+y+', expected: '+expected[i] );
+ } else {
+ delta = abs( y - expected[ i ] );
+ tol = 1.5 * EPS * abs( expected[ i ] );
+ t.ok( delta <= tol, 'within tolerance. sigma: '+sigma[i]+'. y: '+y+'. E: '+expected[ i ]+'. Δ: '+delta+'. tol: '+tol+'.' );
+ }
+ }
+ t.end();
+});