diff --git a/js/index.js b/js/index.js
index f30380f..621f6cd 100644
--- a/js/index.js
+++ b/js/index.js
@@ -1,5 +1,5 @@
 var recquire_t = require('recquire');
 
-var recquire = recquire_t('cg', 'index.js', false, true);
+var recquire = recquire_t('cg', 'index.js', 'intro.js', 'outro.js', false, true);
 
 recquire(__dirname + '/src/', module.exports, -1);
\ No newline at end of file
diff --git a/js/src/2d/sin_sign.js b/js/src/2d/sin_sign.js
index e10a563..53a5ce5 100644
--- a/js/src/2d/sin_sign.js
+++ b/js/src/2d/sin_sign.js
@@ -1,7 +1,31 @@
 
+/**
+ * Computes the cross product of _ab_ and _ac_,
+ * can be interpreted as the sinus sign in a "right-handed" coordinate system
+ * (i.e. clockwise angle values).
+ * 
+ * <p>
+ * Originally implemented as
+ * 
+ *     a[1] * (c[0] - b[0]) + b[1] * (a[0] - c[0]) + c[1] * (b[0] - a[0])
+ *     
+ * with
+ *   - 2 add
+ *   - 3 sub
+ *   - 3 mul
+ *    
+ * Reduced to
+ *
+ *     (b[0] - a[0]) * (c[1] - a[1]) - (b[1] - a[1]) * (c[0] - a[0])
+ *
+ * with
+ *   - 5 sub
+ *   - 2 mul
+ * 
+ */
 
 var sin_sign = function(a, b, c){
-	return a[1] * (c[0] - b[0]) + b[1] * (a[0] - c[0]) + c[1] * (b[0] - a[0]);
+	return (b[0] - a[0]) * (c[1] - a[1]) - (b[1] - a[1]) * (c[0] - a[0]);
 };
 
 
diff --git a/package.json b/package.json
index bac0888..bae6ac8 100644
--- a/package.json
+++ b/package.json
@@ -1,10 +1,10 @@
 {
   "name": "cg",
-  "version": "0.0.1",
+  "version": "0.1.0",
   "description": "cg (computational geometry) algorithms templates for JavaScript",
   "main": "js/index.js",
   "dependencies": {
-    "recquire": "^0.0.0"
+    "recquire": "~0.1.0"
   },
   "devDependencies": {
     "qunit": "git://github.com/gotwarlost/node-qunit.git#istanbul-coverage",
diff --git a/test/js/src/2d/sin_sign.js b/test/js/src/2d/sin_sign.js
index 339a051..a326b4a 100644
--- a/test/js/src/2d/sin_sign.js
+++ b/test/js/src/2d/sin_sign.js
@@ -5,7 +5,6 @@ test('sin_sign', function (assert) {
 	var p = [
 		[0, 0],
 		[0, 1],
-		[0, 2],
 		[1, 0],
 		[1, 1],
 		[1, 2],
@@ -15,14 +14,14 @@ test('sin_sign', function (assert) {
 		[-1, 0]
 	];
 
-	ok(cg.sin_sign(p[0], p[1], p[2]) === 0, '0');
-	ok(cg.sin_sign(p[0], p[1], p[3])   < 0, '45');
-	ok(cg.sin_sign(p[0], p[1], p[4])   < 0, '90');
-	ok(cg.sin_sign(p[0], p[1], p[5])   < 0, '135');
-	ok(cg.sin_sign(p[0], p[1], p[6]) === 0, '180');
-	ok(cg.sin_sign(p[0], p[1], p[7])   > 0, '225');
-	ok(cg.sin_sign(p[0], p[1], p[8])   > 0, '270');
-	ok(cg.sin_sign(p[0], p[1], p[9])   > 0, '315');
+	ok(cg.sin_sign(p[0], p[1], p[0]) === 0, '0');
+	ok(cg.sin_sign(p[0], p[1], p[2])   < 0, '315');
+	ok(cg.sin_sign(p[0], p[1], p[3])   < 0, '270');
+	ok(cg.sin_sign(p[0], p[1], p[4])   < 0, '225');
+	ok(cg.sin_sign(p[0], p[1], p[5]) === 0, '180');
+	ok(cg.sin_sign(p[0], p[1], p[6])   > 0, '135');
+	ok(cg.sin_sign(p[0], p[1], p[7])   > 0, '90');
+	ok(cg.sin_sign(p[0], p[1], p[8])   > 0, '45');