diff --git a/p1/p1/funcs.py b/p1/p1/funcs.py
index fb0222a..f66cfc3 100644
--- a/p1/p1/funcs.py
+++ b/p1/p1/funcs.py
@@ -172,6 +172,10 @@ def plot_mutual_correlation(d1: pd.DataFrame, d2: pd.DataFrame, fname: str = 'xy
 
 def plot_autocorrelation(dat: pd.DataFrame, fname: str = 'x', colour: str = '#1f77b4'):
 	d = auto_correlation(dat.tolist())
+	# exm. TODO: check against matlab.
+	# z = pd.Series([.4, .5, .23, 2.5, -3.6, .4, -0.12, 2.2, 0.02, 14.4])
+	# a = auto_correlation(z.tolist())
+	# print(a)
 	pyplt.plot(range(0, len(d)), d, color=colour)
 	pyplt.title('Autocorrelation of ' + fname + ' (R' + fname + fname + ')')
 	pyplt.xlabel('shift')