feat: add C implementation for math/base/special/atan2

lib/node_modules/@stdlib/math/base/special/atan2/README.md

@@ -86,6 +86,98 @@ 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/atan2.h"
+```
+
+#### stdlib_base_atan2( x )
+
+Compute the angle in the plane (in radians) between the positive x-axis and the ray from `(0,0)` to the point `(x,y)`.
+
+```c
+double out = stdlib_base_atan2( 2.0, 2.0 ); 
+// returns ~0.785
+
+out = stdlib_base_atan2( 6.0, 2.0 );
+// returns ~1.249
+```
+
+The function accepts the following arguments:
+
+-   **x**: `[in] double` input value.
+
+```c
+double stdlib_base_atan2( const double x );
+```
+
+</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/atan2.h"
+#include "stdlib/random/base/randu"
+#include <stdio.h>
+
+int main( void ) {
+    double y;
+    double x;
+    int i;
+
+    for ( i = 0; i < 100; i++ ) {
+        y = stdlib_base_random_randu(100);
+        x = stdlib_base_random_randu(100);
+        printf("y: %.4f, \t x: %.4f, \t atan2(y,x): %.4f\n", y, x, stdlib_base_atan2(y, x));
+    }
+    return 0;
+}
+```
+
+</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/atan2/benchmark/benchmark.native.js

@@ -0,0 +1,62 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2022 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 randu = require( '@stdlib/random/base/randu' );
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+var tryRequire = require( '@stdlib/utils/try-require' );
+var pkg = require( './../package.json' ).name;
+
+
+// VARIABLES //
+
+var atan2 = tryRequire( resolve( __dirname, './../lib/native.js' ) );
+var opts = {
+	'skip': ( atan2 instanceof Error )
+};
+
+
+// MAIN //
+
+bench( pkg+'::native', opts, function benchmark( b ) {
+	var x;
+	var y;
+	var z;
+	var i;
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		x = ( randu()*100.0 ) - 0.0;
+		y = ( randu()*100.0 ) - 0.0;
+		z = Math.atan2( x, y ); // eslint-disable-line stdlib/no-builtin-math
+		if ( isnan( z ) ) {
+			b.fail( 'should not return NaN' );
+		}
+	}
+	b.toc();
+	if ( isnan( z ) ) {
+		b.fail( 'should not return NaN' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});

lib/node_modules/@stdlib/math/base/special/atan2/benchmark/c/native/Makefile

@@ -0,0 +1,107 @@
+#/
+# @license Apache-2.0
+#
+# Copyright (c) 2018 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 := @
+endif
+
+# Determine the OS:
+#
+# [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
+endif
+endif
+endif
+
+# Define the program used for compiling C source files:
+ifdef C_COMPILER
+	CC := $(C_COMPILER)
+else
+	CC := gcc
+endif
+
+# Define the command-line options when compiling C files:
+CFLAGS ?= \
+	-std=c99 \
+	-O3 \
+	-Wall \
+	-pedantic
+
+# Determine whether to generate [position independent code][1]:
+#
+# [1]: https://gcc.gnu.org/onlinedocs/gcc/Code-Gen-Options.html#Code-Gen-Options
+# [2]: http://stackoverflow.com/questions/5311515/gcc-fpic-option
+ifeq ($(OS), WINNT)
+	fPIC ?=
+else
+	fPIC ?= -fPIC
+endif
+
+# List of C targets:
+c_targets := benchmark.out
+
+
+# TARGETS #
+
+# Default target.
+#
+# This target is the default target.
+
+all: $(c_targets)
+
+.PHONY: all
+
+
+# Compile C source.
+#
+# This target compiles C source files.
+
+$(c_targets): %.out: %.c
+	$(QUIET) $(CC) $(CFLAGS) $(fPIC) -o $@ $< -lm
+
+
+# Run a benchmark.
+#
+# This target runs a benchmark.
+
+run: $(c_targets)
+	$(QUIET) ./$<
+
+.PHONY: run
+
+
+# Perform clean-up.
+#
+# This target removes generated files.
+
+clean:
+	$(QUIET) -rm -f *.o *.out
+
+.PHONY: clean