diff --git a/bisection.h b/bisection.h
index acb31f6..a2a44df 100644
--- a/bisection.h
+++ b/bisection.h
@@ -1,6 +1,6 @@
 #ifndef _BISECTION_H
 #define _BISECTION_H
-//general bisection search
+//general bisection search between dm and hm
 //returns dm-1 on failure, otherwise number between dm and hm
 //cmp returns 0 on equal, >0 if first > second argument
 
@@ -39,15 +39,15 @@ int interpolation_find(INDEX dm0, INDEX high, const SUBJECT *x, const SUBJECT *b
 		{
 		d1=(*dist)(x,base+low*lead_dimension_base);
 		d2=(*dist)(base+high*lead_dimension_base,x);
-		cout << "intlp "<<low<<" "<<high<<" "<<d1<<" "<<d2<,endl
-		if(d1<=0 || d2 >=0)  break;
+		cout << "intlp "<<low<<" "<<high<<" "<<d1<<" "<<d2<<endl;
+		if(d1<=0 || d2 <=0)  break;
 		d3=(*dist)(base+high*lead_dimension_base,base+low*lead_dimension_base);
-	        mid = low + (int)((d1 * (high-low)) / d3+.5); 
+	        mid = low + (int)((d1 * (high-low)) / d3); 
+		if(mid<low||mid>high) laerror("interpolation_find: error in distance function");
 		d4=(*dist)(x,base+mid*lead_dimension_base);
-		cout << "intlp2 "<<mid<<" "<<d3<<" "<<d4<<endl;
                 if(d4>0)
                     low = mid + 1;
-                else if(d3<0)
+                else if(d4<0)
                     high = mid - 1;
                 else
                     return mid;