Fix divide by zero in sinefit

Makefile

@@ -5,7 +5,7 @@ all: test
 
 test:
 ifeq ($(INSIDE_EMACS), t)
-	@make test_trainola3
+	@make test_sinefit
 else
 	@echo 'No test suite for nilmtools.  Try "make install"'
 endif
@@ -58,6 +58,14 @@ test_prep: /tmp/raw.dat
 	nilmtools/prep.py -c 2 /test/raw /test/sinefit /test/prep
 	nilmtool extract -s min -e max /test/prep | head -20
 
+test_sinefit:
+	make install >/dev/null 2>&1
+	-nilmtool destroy -R /test/sinefit
+	nilmtool create /test/sinefit float32_3
+	nilmtools/sinefit.py -c 5 -s '2013/03/25 09:11:00' \
+	-e '2013/03/25 10:11:00' /sharon/raw /test/sinefit
+	nilmtool extract -s min -e max /test/sinefit | head -20
+
 test_decimate:
 	-@nilmtool destroy /lees-compressor/no-leak/raw/4 || true
 	-@nilmtool destroy /lees-compressor/no-leak/raw/16 || true

extras/sample-cron-scripts/crontab

@@ -1,5 +1,8 @@
 # Install this by running "crontab crontab" (will replace existing crontab)
 
+SHELL=/bin/bash
+PATH=/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin
+
 # m h dom mon dow cmd
 
 # Run NilmDB processing every 5 minutes
@@ -7,3 +10,6 @@
 
 # Try frequently restarting the capture process in case it died
 */5 * * * * chronic /home/nilm/data/capture.sh
+
+# Run fsck at startup
+@reboot chronic nilmdb-fsck --fix --no-data /home/nilm/data/db/

nilmtools/math.py

@@ -37,17 +37,21 @@ def sfit4(data, fs):
     i = argmax(F[0:int(N/2)] + F[1:int(N/2+1)])
 
     # Interpolate FFT to get a better result (from Markus [B37])
-    U1 = real(Fc[i])
-    U2 = real(Fc[i+1])
-    V1 = imag(Fc[i])
-    V2 = imag(Fc[i+1])
-    n = 2 * pi / N
-    ni1 = n * i
-    ni2 = n * (i+1)
-    K = ((V2-V1)*sin(ni1) + (U2-U1)*cos(ni1)) / (U2-U1)
-    Z1 = V1 * (K - cos(ni1)) / sin(ni1) + U1
-    Z2 = V2 * (K - cos(ni2)) / sin(ni2) + U2
-    i = arccos((Z2*cos(ni2) - Z1*cos(ni1)) / (Z2-Z1)) / n
+    try:
+        U1 = real(Fc[i])
+        U2 = real(Fc[i+1])
+        V1 = imag(Fc[i])
+        V2 = imag(Fc[i+1])
+        n = 2 * pi / N
+        ni1 = n * i
+        ni2 = n * (i+1)
+        K = ((V2-V1)*sin(ni1) + (U2-U1)*cos(ni1)) / (U2-U1)
+        Z1 = V1 * (K - cos(ni1)) / sin(ni1) + U1
+        Z2 = V2 * (K - cos(ni2)) / sin(ni2) + U2
+        i = arccos((Z2*cos(ni2) - Z1*cos(ni1)) / (Z2-Z1)) / n
+    except Exception:
+        # Just go with the biggest FFT peak
+        i = argmax(F[0:int(N/2)])
 
     # Convert to Hz
     f0 = i * float(fs) / N

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