feat: add C implementation for stats/base/dists/chi/skewness

lib/node_modules/@stdlib/stats/base/dists/chi/skewness/benchmark/benchmark.native.js

@@ -1,7 +1,7 @@
 /**
 * @license Apache-2.0
 *
-* Copyright (c) 2025 The Stdlib Authors.
+* 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.
@@ -23,8 +23,8 @@
 var resolve = require( 'path' ).resolve;
 var bench = require( '@stdlib/bench' );
 var uniform = require( '@stdlib/random/array/uniform' );
-var format = require( '@stdlib/string/format' );
 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;
 
@@ -39,16 +39,16 @@
 
 // MAIN //
 
-bench( format( '%s::native', pkg ), opts, function benchmark( b ) {
-	var opts;
+bench( pkg+'::native', opts, function benchmark( b ) {
+	var kopts;
 	var k;
 	var y;
 	var i;
 
-	opts = {
+	kopts = {
 		'dtype': 'float64'
 	};
-	k = uniform( 100, 1.0, 10.0, opts );
+	k = uniform( 100, EPS, 20.0, kopts );
 
 	b.tic();
 	for ( i = 0; i < b.iterations; i++ ) {

lib/node_modules/@stdlib/stats/base/dists/chi/skewness/benchmark/c/Makefile

@@ -1,7 +1,7 @@
 #/
 # @license Apache-2.0
 #
-# Copyright (c) 2025 The Stdlib Authors.
+# 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.
@@ -24,10 +24,6 @@ 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
@@ -45,101 +41,46 @@ 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
 

lib/node_modules/@stdlib/stats/base/dists/chi/skewness/benchmark/c/benchmark.c

@@ -1,7 +1,7 @@
 /**
 * @license Apache-2.0
 *
-* Copyright (c) 2025 The Stdlib Authors.
+* 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.

lib/node_modules/@stdlib/stats/base/dists/chi/skewness/binding.gyp

@@ -1,6 +1,6 @@
 # @license Apache-2.0
 #
-# Copyright (c) 2025 The Stdlib Authors.
+# 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.

lib/node_modules/@stdlib/stats/base/dists/chi/skewness/examples/c/Makefile

@@ -1,7 +1,7 @@
 #/
 # @license Apache-2.0
 #
-# Copyright (c) 2025 The Stdlib Authors.
+# 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.
@@ -24,10 +24,6 @@ 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
@@ -45,101 +41,46 @@ 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
 

lib/node_modules/@stdlib/stats/base/dists/chi/skewness/examples/c/example.c

@@ -1,7 +1,7 @@
 /**
 * @license Apache-2.0
 *
-* Copyright (c) 2025 The Stdlib Authors.
+* 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.
@@ -33,6 +33,6 @@ int main( void ) {
 	for ( i = 0; i < 25; i++ ) {
 		k = random_uniform( 1.0, 10.0 );
 		y = stdlib_base_dists_chi_skewness( k );
-		printf( "k: %lf, skew(X,k): %lf\n", k, y );
+		printf( "k: %lf, skewness(X,k): %lf\n", k, y );
 	}
 }

lib/node_modules/@stdlib/stats/base/dists/chi/skewness/include.gypi

@@ -1,6 +1,6 @@
 # @license Apache-2.0
 #
-# Copyright (c) 2025 The Stdlib Authors.
+# 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.

lib/node_modules/@stdlib/stats/base/dists/chi/skewness/include/stdlib/stats/base/dists/chi/skewness.h

@@ -1,7 +1,7 @@
 /**
 * @license Apache-2.0
 *
-* Copyright (c) 2025 The Stdlib Authors.
+* 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.
@@ -28,6 +28,9 @@ extern "C" {
 
 /**
 * Returns the skewness of a chi distribution.
+*
+* @param k    degrees of freedom
+* @return     skewness
 */
 double stdlib_base_dists_chi_skewness( const double k );
 

lib/node_modules/@stdlib/stats/base/dists/chi/skewness/lib/native.js

@@ -1,7 +1,7 @@
 /**
 * @license Apache-2.0
 *
-* Copyright (c) 2025 The Stdlib Authors.
+* 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.
@@ -33,19 +33,19 @@ var addon = require( './../src/addon.node' );
 * @returns {number} skewness
 *
 * @example
-* var y = skewness( 9.0 );
+* var v = skewness( 9.0 );
 * // returns ~0.252
 *
 * @example
 * var v = skewness( 1.0 );
 * // returns ~0.995
 *
 * @example
-* var v = skewness( 2.0 );
-* // returns ~0.631
+* var v = skewness( -0.2 );
+* // returns NaN
 *
 * @example
-* var y = skewness( NaN );
+* var v = skewness( NaN );
 * // returns NaN
 */
 function skewness( k ) {