Add STC, although it works very slow

stc.py

@@ -0,0 +1,19 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+"""
+Created on Tue May 16 13:28:17 2017
+
+@author: ycan
+
+Spike-triggered covariance
+"""
+
+def stc(spikes,stimulus,filter_length):
+    covariance=np.matrix(np.zeros(filter_length,filter_length))
+    sta=sta(spikes,stimulus,filter_length)
+    for i in range(filter_length,total_frames):
+        snippet=stimulus[i:i-filter_length:-1]
+        # Snippets are inverted before being added
+        snpta=[snippet-sta]
+        covariance=covariance+snpta.T*snpta*spikes[i]
+    return covariance/fil