From 992e09b2a79ad9eeb4d3164712d49f8778c74f7f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Petr=C3=B4nio=20C=C3=A2ndido?= <petronio.candido@gmail.com>
Date: Thu, 28 Jun 2018 13:47:34 -0300
Subject: [PATCH] bugfix in Transformation.Differential

---
 pyFTS/common/Transformations.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pyFTS/common/Transformations.py b/pyFTS/common/Transformations.py
index 6693614..a14eacd 100644
--- a/pyFTS/common/Transformations.py
+++ b/pyFTS/common/Transformations.py
@@ -64,7 +64,7 @@ class Differential(Transformation):
             data = data.tolist()
 
         n = len(data)
-        diff = [data[t - self.lag] - data[t] for t in np.arange(self.lag, n)]
+        diff = [data[t] - data[t - self.lag] for t in np.arange(self.lag, n)]
         for t in np.arange(0, self.lag): diff.insert(0, 0)
         return diff