Refactor to correctly handle signed zeros

kgryte · kgryte · commit 0eb11b4c3da0 · 2018-05-13T23:52:57.000-07:00
diff --git a/lib/node_modules/@stdlib/stats/incr/max/README.md b/lib/node_modules/@stdlib/stats/incr/max/README.md
@@ -66,7 +66,7 @@ max = accumulator();
 
 ## Notes
 
--   Input values are **not** type checked. If non-numeric inputs are possible, you are advised to type check and handle accordingly **before** passing the value to the accumulator function.
+-   Input values are **not** type checked. If provided `NaN`, the accumulated value is `NaN` for **all** future invocations. If non-numeric inputs are possible, you are advised to type check and handle accordingly **before** passing the value to the accumulator function.
 
 </section>
 
diff --git a/lib/node_modules/@stdlib/stats/incr/max/docs/repl.txt b/lib/node_modules/@stdlib/stats/incr/max/docs/repl.txt
@@ -7,6 +7,8 @@
     value. If not provided a value, the accumulator function returns the current
     maximum value.
 
+    If provided `NaN`, the maximum value is `NaN` for all future invocations.
+
     Returns
     -------
     acc: Function
diff --git a/lib/node_modules/@stdlib/stats/incr/max/lib/main.js b/lib/node_modules/@stdlib/stats/incr/max/lib/main.js
@@ -18,6 +18,12 @@
 
 'use strict';
 
+// MODULES //
+
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+var isPositiveZero = require( '@stdlib/math/base/assert/is-positive-zero' );
+
+
 // MAIN //
 
 /**
@@ -29,7 +35,7 @@
 * var accumulator = incrmax();
 */
 function incrmax() {
-	var max = null;
+	var max;
 	return accumulator;
 
 	/**
@@ -57,9 +63,14 @@ function incrmax() {
 	*/
 	function accumulator( x ) {
 		if ( arguments.length === 0 ) {
-			return max;
+			return ( max === void 0 ) ? null : max;
 		}
-		if ( x > max || max === null ) {
+		if (
+			max === void 0 ||
+			x > max ||
+			isnan( x ) ||
+			( x === max && isPositiveZero( x ) )
+		) {
 			max = x;
 		}
 		return max;
diff --git a/lib/node_modules/@stdlib/stats/incr/max/test/test.js b/lib/node_modules/@stdlib/stats/incr/max/test/test.js
@@ -21,6 +21,9 @@
 // MODULES //
 
 var tape = require( 'tape' );
+var isNegativeZero = require( '@stdlib/math/base/assert/is-negative-zero' );
+var isPositiveZero = require( '@stdlib/math/base/assert/is-positive-zero' );
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var incrmax = require( './../lib' );
 
 
@@ -87,3 +90,35 @@ tape( 'if not provided an input value, the accumulator function returns the curr
 	t.equal( acc(), 3.0, 'returns the current accumulated maximum value' );
 	t.end();
 });
+
+tape( 'the accumulator function correctly handles signed zeros', function test( t ) {
+	var acc;
+	var v;
+
+	acc = incrmax();
+
+	v = acc( -0.0 );
+	t.equal( isNegativeZero( v ), true, 'returns expected value' );
+
+	v = acc( 0.0 );
+	t.equal( isPositiveZero( v ), true, 'returns expected value' );
+
+	v = acc( -0.0 );
+	t.equal( isPositiveZero( v ), true, 'returns expected value' );
+
+	t.end();
+});
+
+tape( 'if provided a `NaN`, the accumulator function returns `NaN` for all future invocations', function test( t ) {
+	var data;
+	var acc;
+	var i;
+
+	data = [ 2.0, NaN, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0 ];
+	acc = incrmax();
+	for ( i = 0; i < data.length; i++ ) {
+		acc( data[ i ] );
+	}
+	t.equal( isnan( acc() ), true, 'returns expected value' );
+	t.end();
+});
