fix: correctly handle signed zeroes in math/base/special/atanf

PR-URL: 	#2115
Ref: #2113
Reviewed-by: Athan Reines <[email protected]>

Author: gunjjoshi

lib/node_modules/@stdlib/math/base/special/atanf/lib/main.js

@@ -86,8 +86,8 @@ function atanf( x ) {
 	var y;
 	var z;
 
-	if ( isnanf( x ) ) {
-		return NaN;
+	if ( isnanf( x ) || x === 0.0 ) {
+		return x;
 	}
 	x = float64ToFloat32( x );
 	if ( x < 0.0 ) {

lib/node_modules/@stdlib/math/base/special/atanf/src/main.c

@@ -88,8 +88,8 @@ float stdlib_base_atanf( const float x ) {
 	float y;
 	float z;
 
-	if ( stdlib_base_is_nanf( x ) ) {
-		return 0.0f / 0.0f; // NaN
+	if ( stdlib_base_is_nanf( x ) || x == 0.0f ) {
+		return x;
 	}
 	ax = x;
 	if ( x < 0.0f ) {

lib/node_modules/@stdlib/math/base/special/atanf/test/test.js

@@ -25,6 +25,8 @@ var isnanf = require( '@stdlib/math/base/assert/is-nanf' );
 var abs = require( '@stdlib/math/base/special/abs' );
 var EPS = require( '@stdlib/constants/float32/eps' );
 var float64ToFloat32 = require( '@stdlib/number/float64/base/to-float32' );
+var isNegativeZerof = require( '@stdlib/math/base/assert/is-negative-zerof' );
+var isPositiveZerof = require( '@stdlib/math/base/assert/is-positive-zerof' );
 var atanf = require( './../lib' );
 
 
@@ -396,3 +398,21 @@ tape( 'the function returns `NaN` if provided `NaN`', function test( t ) {
 	t.equal( isnanf( v ), true, 'returns NaN' );
 	t.end();
 });
+
+tape( 'the function returns `-0` if provided `-0`', function test( t ) {
+	var v = atanf( -0.0 );
+	t.equal( isNegativeZerof( v ), true, 'returns -0' );
+	t.end();
+});
+
+tape( 'the function returns `0` if provided +0', function test( t ) {
+	var v;
+
+	v = atanf( 0.0 );
+	t.equal( isPositiveZerof( v ), true, 'returns +0' );
+
+	v = atanf( +0.0 );
+	t.equal( isPositiveZerof( v ), true, 'returns +0' );
+
+	t.end();
+});

lib/node_modules/@stdlib/math/base/special/atanf/test/test.native.js

@@ -26,6 +26,8 @@ var isnanf = require( '@stdlib/math/base/assert/is-nanf' );
 var abs = require( '@stdlib/math/base/special/abs' );
 var EPS = require( '@stdlib/constants/float32/eps' );
 var float64ToFloat32 = require( '@stdlib/number/float64/base/to-float32' );
+var isNegativeZerof = require( '@stdlib/math/base/assert/is-negative-zerof' );
+var isPositiveZerof = require( '@stdlib/math/base/assert/is-positive-zerof' );
 var tryRequire = require( '@stdlib/utils/try-require' );
 
 
@@ -405,3 +407,21 @@ tape( 'the function returns `NaN` if provided `NaN`', opts, function test( t ) {
 	t.equal( isnanf( v ), true, 'returns NaN' );
 	t.end();
 });
+
+tape( 'the function returns `-0` if provided `-0`', opts, function test( t ) {
+	var v = atanf( -0.0 );
+	t.equal( isNegativeZerof( v ), true, 'returns -0' );
+	t.end();
+});
+
+tape( 'the function returns `0` if provided +0', opts, function test( t ) {
+	var v;
+
+	v = atanf( 0.0 );
+	t.equal( isPositiveZerof( v ), true, 'returns +0' );
+
+	v = atanf( +0.0 );
+	t.equal( isPositiveZerof( v ), true, 'returns +0' );
+
+	t.end();
+});