diff --git a/tutorials/pyroot/zdemo.py b/tutorials/pyroot/zdemo.py
index 28db48f..603c7cb 100644
--- a/tutorials/pyroot/zdemo.py
+++ b/tutorials/pyroot/zdemo.py
@@ -18,7 +18,6 @@
import ROOT
from array import array
-from math import *
NMAX = 20
Z = array( 'f', [0.]*NMAX )
@@ -31,6 +30,7 @@ saves = {}
#_______________________________________________________________________________
def hz_calc( ENERG, DENS, TGRAD, PTMIN, PTMAX, DELP ):
+ from math import sin, cos, sqrt
global NLOOP
global Z, HZ, PT, INVSIG
@@ -104,9 +104,11 @@ def hz_calc( ENERG, DENS, TGRAD, PTMIN, PTMAX, DELP ):
#_______________________________________________________________________________
def zdemo():
+ from array import array
global NLOOP
global Z, HZ, PT, INVSIG
global saves
+ global hz_calc
# Create a new canvas.
c1 = ROOT.TCanvas( 'zdemo', 'Monte Carlo Study of Z scaling', 10, 40, 800, 600 )