From 0cf2db6c5ec645c124d2b8b5e861d43627fa4970 Mon Sep 17 00:00:00 2001
From: Jim Paris <jim@jtan.com>
Date: Fri, 14 Feb 2014 15:55:42 -0500
Subject: [PATCH] Fix divide by zero in sinefit

---
 nilmtools/sinefit.py | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/nilmtools/sinefit.py b/nilmtools/sinefit.py
index 850e66c..6fd28b4 100755
--- a/nilmtools/sinefit.py
+++ b/nilmtools/sinefit.py
@@ -96,8 +96,11 @@ def process(data, interval, args, insert_function, final):
     rows = data.shape[0]
 
     # Estimate sampling frequency from timestamps
-    fs = (rows-1) / (timestamp_to_seconds(data[-1][0]) -
-                     timestamp_to_seconds(data[0][0]))
+    ts_min = timestamp_to_seconds(data[0][0])
+    ts_max = timestamp_to_seconds(data[-1][0])
+    if ts_min >= ts_max:
+        return 0
+    fs = (rows-1) / (ts_max - ts_min)
 
     # Pull out about 3.5 periods of data at once;
     # we'll expect to match 3 zero crossings in each window