diff --git a/netflow/js/core/activation.js b/netflow/js/core/activation.js
index 78ec1f0..6e1ef8e 100644
--- a/netflow/js/core/activation.js
+++ b/netflow/js/core/activation.js
@@ -11,4 +11,7 @@ function ReLu(x, def){
         return Math.max(0, x);
     else
         return (x <= 0)?0:x;
-}
\ No newline at end of file
+}
+function Sigmoid(x){
+    return 1 / (1 + Math.exp(-x));
+}