Add C implementation

Author: kgryte

lib/node_modules/@stdlib/math/base/special/cabs/README.md

@@ -20,7 +20,7 @@ limitations under the License.
 
 # Absolute Value
 
-> Compute an [absolute value][absolute-value] of a double-precision [complex][@stdlib/complex/float64] floating-point number.
+> Compute the [absolute value][absolute-value] of a double-precision [complex][@stdlib/complex/float64] floating-point number.
 
 <section class="intro">
 
@@ -89,6 +89,96 @@ for ( i = 0; i < 100; i++ ) {
 
 <!-- /.examples -->
 
+<!-- C interface documentation. -->
+
+* * *
+
+<section class="c">
+
+## C APIs
+
+<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->
+
+<section class="intro">
+
+</section>
+
+<!-- /.intro -->
+
+<!-- C usage documentation. -->
+
+<section class="usage">
+
+### Usage
+
+```c
+#include "stdlib/math/base/special/cabs.h"
+```
+
+#### stdlib_base_cabs( z )
+
+Computes an [absolute value][absolute-value] of a double-precision complex floating-point number.
+
+```c
+#include <complex.h>
+
+double y = stdlib_base_cabs( 5.0+3.0*I );
+// returns ~5.83
+```
+
+The function accepts the following arguments:
+
+-   **z**: `[in] double complex` input value.
+
+```c
+double stdlib_base_cabs( const double complex z );
+```
+
+</section>
+
+<!-- /.usage -->
+
+<!-- C API usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="notes">
+
+</section>
+
+<!-- /.notes -->
+
+<!-- C API usage examples. -->
+
+<section class="examples">
+
+### Examples
+
+```c
+#include "stdlib/math/base/special/cabs.h"
+#include <stdio.h>
+#include <complex.h>
+
+int main() {
+    double complex x[] = { 3.14+1.0*I, -3.14-1.0*I, 0.0+0.0*I, 0.0/0.0+0.0/0.0*I };
+
+    double complex v;
+    double y;
+    int i;
+    for ( i = 0; i < 4; i++ ) {
+        v = x[ i ];
+        y = stdlib_base_cabs( v );
+        printf( "f(%lf + %lf) = %lf\n", creal( v ), cimag( v ), y );
+    }
+}
+```
+
+</section>
+
+<!-- /.examples -->
+
+</section>
+
+<!-- /.c -->
+
 <!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->
 
 <section class="related">

lib/node_modules/@stdlib/math/base/special/cabs/benchmark/benchmark.js

@@ -1,7 +1,7 @@
 /**
 * @license Apache-2.0
 *
-* Copyright (c) 2018 The Stdlib Authors.
+* Copyright (c) 2021 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/math/base/special/cabs/benchmark/c/Makefile

@@ -1,7 +1,7 @@
 #/
 # @license Apache-2.0
 #
-# Copyright (c) 2018 The Stdlib Authors.
+# Copyright (c) 2021 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.
@@ -16,14 +16,15 @@
 # limitations under the License.
 #/
 
-
 # VARIABLES #
 
 ifndef VERBOSE
 	QUIET := @
+else
+	QUIET :=
 endif
 
-# Determine the OS:
+# Determine the OS ([1][1], [2][2]).
 #
 # [1]: https://en.wikipedia.org/wiki/Uname#Examples
 # [2]: http://stackoverflow.com/a/27776822/2225624
@@ -36,6 +37,10 @@ ifneq (, $(findstring MSYS,$(OS)))
 else
 ifneq (, $(findstring CYGWIN,$(OS)))
 	OS := WINNT
+else
+ifneq (, $(findstring Windows_NT,$(OS)))
+	OS := WINNT
+endif
 endif
 endif
 endif
@@ -54,7 +59,7 @@ CFLAGS ?= \
 	-Wall \
 	-pedantic
 
-# Determine whether to generate [position independent code][1]:
+# 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
@@ -68,39 +73,53 @@ endif
 c_targets := benchmark.out
 
 
-# TARGETS #
+# RULES #
 
-# Default target.
+#/
+# Compiles C source files.
 #
-# This target is the default target.
-
+# @param {string} [C_COMPILER] - C compiler (e.g., `gcc`)
+# @param {string} [CFLAGS] - C compiler options
+# @param {(string|void)} [fPIC] - compiler flag indicating whether to generate position independent code (e.g., `-fPIC`)
+#
+# @example
+# make
+#
+# @example
+# make all
+#/
 all: $(c_targets)
 
 .PHONY: all
 
-
-# Compile C source.
+#/
+# Compiles C source files.
 #
-# This target compiles C source files.
-
+# @private
+# @param {string} CC - C compiler
+# @param {string} CFLAGS - C compiler flags
+# @param {(string|void)} fPIC - compiler flag indicating whether to generate position independent code
+#/
 $(c_targets): %.out: %.c
 	$(QUIET) $(CC) $(CFLAGS) $(fPIC) -o $@ $< -lm
 
-
-# Run a benchmark.
+#/
+# Runs compiled benchmarks.
 #
-# This target runs a benchmark.
-
+# @example
+# make run
+#/
 run: $(c_targets)
 	$(QUIET) ./$<
 
 .PHONY: run
 
-
-# Perform clean-up.
+#/
+# Removes generated files.
 #
-# This target removes generated files.
-
+# @example
+# make clean
+#/
 clean:
 	$(QUIET) -rm -f *.o *.out
 

lib/node_modules/@stdlib/math/base/special/cabs/benchmark/c/benchmark.c

@@ -77,9 +77,9 @@ double tic() {
 }
 
 /**
-* Generates a random double on the interval [0,1].
+* Generates a random number on the interval [0,1].
 *
-* @return random double
+* @return random number
 */
 double rand_double() {
 	int r = rand();
@@ -92,6 +92,7 @@ double rand_double() {
 * @return elapsed time in seconds
 */
 double benchmark() {
+	double complex z;
 	double elapsed;
 	double re;
 	double im;
@@ -103,7 +104,7 @@ double benchmark() {
 	for ( i = 0; i < ITERATIONS; i++ ) {
 		re = ( 1000.0*rand_double() ) - 500.0;
 		im = ( 1000.0*rand_double() ) - 500.0;
-		double complex z = re + im*I;
+		z = re + im*I;
 		y = cabs( z );
 		if ( y != y ) {
 			printf( "should not return NaN\n" );