--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/javascript/d3/src/core/sum.js	Thu Apr 10 14:20:23 2014 +0200
@@ -0,0 +1,14 @@
+d3.sum = function(array, f) {
+  var s = 0,
+      n = array.length,
+      a,
+      i = -1;
+
+  if (arguments.length === 1) {
+    while (++i < n) if (!isNaN(a = +array[i])) s += a;
+  } else {
+    while (++i < n) if (!isNaN(a = +f.call(array, array[i], i))) s += a;
+  }
+
+  return s;
+};