Index: trunk/Mars/manalysis/MSoftwareTrigger.cc
===================================================================
--- trunk/Mars/manalysis/MSoftwareTrigger.cc	(revision 18476)
+++ trunk/Mars/manalysis/MSoftwareTrigger.cc	(revision 18477)
@@ -126,4 +126,5 @@
         Float_t *sum = buf.GetArray()+(hw/9)*num;
 
+        // Sum all nine pixel of one trigger patch
         for (const Float_t *ptr=raw+beg; ptr<raw+end; ptr++, sum++)
             *sum += *ptr;