diff --git a/ostap/utils/utils.py b/ostap/utils/utils.py
index 2912cdcd..81311233 100644
--- a/ostap/utils/utils.py
+++ b/ostap/utils/utils.py
@@ -850,7 +850,8 @@ def n ( self )  :
 
     def __len__     ( self ) :
 
-        n = self.__n 
+        n = self.__n
+        e = self.__edges 
         return n + 1 if e else n - 1 
 
     def __iter__    ( self ) :
@@ -922,13 +923,16 @@ def __iter__    ( self ) :
         fn = 1.0 / float ( n )
         e  = self.edges
 
+        lmn = self.__lmin
+        lmx = self.__lmx
+        
         if e : yield self.vmin
         
         for i in range ( 1 , n  ) :
             #
             f2 = i * fn
             f1 = 1 - f2
-            yield 10.0 ** ( self.__lmin * f1 + f2 * self.__lmax ) 
+            yield 10.0 ** ( lmn * f1 + f2 * lmx ) 
             
         if e : yield self.vmax