JAL-3858 don’t divide if we only had one value to count

diff --git a/src/jalview/datamodel/ContactListImpl.java b/src/jalview/datamodel/ContactListImpl.java
index bb31c5d..7058ac7 100644 (file)
--- a/src/jalview/datamodel/ContactListImpl.java
+++ b/src/jalview/datamodel/ContactListImpl.java
@@ -88,7 +88,7 @@ public class ContactListImpl implements ContactListI
         }
       }
     }
-    if (tot > 0)
+    if (tot > 0 && to_column>from_column)
     {
       cr.setMean(tot / (1 + to_column - from_column));
     }