feat(sum): create sum filter

src/_filter/math/sum.js

@@ -0,0 +1,23 @@
+/**
+ * @ngdoc filter
+ * @name sum
+ * @kind function
+ *
+ * @description
+ * Sum up all values within an array
+ *
+ */
+
+angular.module('a8m.math.sum', [])
+
+  .filter('sum', function () {
+    return function (input, initial) {
+
+      return (!isArray(input)) ? input :
+        input.reduce(function(prev, curr) {
+          return prev + curr;
+        }, initial || 0);
+
+    }
+
+  });