diff --git a/py/mains/decrease_nbody.py b/py/mains/decrease_nbody.py
index c51cb1576ff8e7e8847218100caedf61724c16eb..e2cee90b1818d73feebefbd4d66c282dee9bc241 100755
--- a/py/mains/decrease_nbody.py
+++ b/py/mains/decrease_nbody.py
@@ -17,6 +17,7 @@
 # unsio module loading
 # ==> do not forget to update PYTHONPATH environment variable with
 #     unsio location path
+from __future__ import print_function
 from unsio import *
 
 import numpy as np
@@ -33,7 +34,7 @@ def compute(file,out,comp,take,bits,mmult):
     if uns.nextFrame(bits):
         unso=CunsOut(out,"gadget2")
         ok,tsnap=uns.getValueF("time") # return snasphot time
-        print "Snapshot time : ","%.03f"%tsnap
+        print ("Snapshot time : ","%.03f"%tsnap)
         unso.setValueF("time",tsnap) # save snapshot time
 
         # loop on all components stored in comp variable
@@ -68,85 +69,85 @@ def printAndSaveProp(uns,unso,comp,take,mmult):
     Component : [%s]
     ----------------------------------------------
     """
-    print info % (comp)
+    print (info % (comp))
     # return a 1D numpy data array with mass
     ok,mass=uns.getArrayF(comp,"mass")
     if ok:
-        print "mass =",mass.size,mass
+        print ("mass =",mass.size,mass)
         mass=keepEveryTake(mass,1,take)
-	if mmult==1:
+        if mmult==1:
             mass=mass*take # multiply mass by take
-        print "mass =",mass.size,mass
+        print ("mass =",mass.size,mass)
         unso.setArrayF(comp,"mass",mass) # save mass
         
     # return a 1D numpy data array with pos
     ok,pos=uns.getArrayF(comp,"pos")
     if ok:
-        print "pos =",pos
+        print ("pos =",pos)
         pos=keepEveryTake(pos,3,take)
         unso.setArrayF(comp,"pos",pos) # save pos
         
     # return a 1D numpy data array with vel
     ok,vel=uns.getArrayF(comp,"vel")
     if ok:
-        print "vel =",vel
+        print ("vel =",vel)
         vel=keepEveryTake(vel,3,take)
         unso.setArrayF(comp,"vel",vel) # save vel
 
     # return a 1D numpy data array with acc 
     ok,acc=uns.getArrayF(comp,"acc")
     if ok:
-        print "acc =",acc
+        print ("acc =",acc)
         acc=keepEveryTake(acc,3,take)
         unso.setArrayF(comp,"acc",acc) # save vel
 
    # return a 1D numpy data array with rho
     ok,rho=uns.getArrayF(comp,"rho")
     if ok:
-        print "rho =",rho
+        print ("rho =",rho)
         rho=keepEveryTake(rho,1,take)
         unso.setArrayF(comp,"rho",rho) # save rho
 
     # return a 1D numpy data array with temperature
     ok,temp=uns.getArrayF(comp,"temp")
     if ok:
-        print "temp =",temp
+        print ("temp =",temp)
         temp=keepEveryTake(temp,1,take)
         unso.setArrayF(comp,"temp",temp) # save temperature
 
     # return a 1D numpy data array with internal energy (U)
     ok,u=uns.getArrayF(comp,"u")
     if ok:
-        print "u =",u.size,u.dtype,u
+        print ("u =",u.size,u.dtype,u)
         u=keepEveryTake(u,1,take)
-        print "u =",u.size,u.dtype,u
+        print ("u =",u.size,u.dtype,u)
         unso.setArrayF(comp,"u",u) # save internal energy
 
     # return a 1D numpy data array with hsml
     ok,hsml=uns.getArrayF(comp,"hsml")
     if ok:
-        print "hsml =",hsml
+        print ("hsml =",hsml)
         hsml=keepEveryTake(hsml,1,take)
         unso.setArrayF(comp,"hsml",hsml) # save hsml
 
     # return a 1D numpy data array with particles age
     ok,age=uns.getArrayF(comp,"age")
     if ok:
-        print "age =",age
+        print ("age =",age)
         age=keepEveryTake(age,1,take)
         unso.setArrayF(comp,"age",age) # save age
 
     # return a 1D numpy data array with mettalicity
     ok,metal=uns.getArrayF(comp,"metal")
     if ok:
-        print "metal =",metal
+        print ("metal =",metal)
         metal=keepEveryTake(metal,1,take)
         unso.setArrayF(comp,"metal",metal) # save mettalicity
 
     # return a 1D numpy data array with potential 
     ok,pot=uns.getArrayF(comp,"pot")
     if ok:
-        print "pot =",pot
+        print ("pot =",pot)
         pot=keepEveryTake(pot,1,take)
         unso.setArrayF(comp,"pot",pot) # save mettalicity
 
@@ -155,7 +156,7 @@ def printAndSaveProp(uns,unso,comp,take,mmult):
     # return a 1D numy data array with id
     ok,indexes=uns.getArrayI(comp,"id")
     if ok:
-        print "indexes =", indexes
+        print ("indexes =", indexes)
         indexes=keepEveryTake(indexes,1,take)
         unso.setArrayI(comp,"id",indexes) # save id
 
@@ -175,7 +176,7 @@ def main(argv):
         opts,args=getopt.getopt(argv,"hi:o:k:c:b:m:",["in=","out=","take=","comp=","bits=","mmult="])
 
     except getopt.GetoptError:
-        print "\nUnknown parameters, please check ....\n\n"
+        print ("\nUnknown parameters, please check ....\n\n")
         printHelp(prog)
         sys.exit()
     for opt, arg in opts:
@@ -192,14 +193,14 @@ def main(argv):
             take = int(arg)
         elif opt in ("-b", "--bits"):
             bits = arg
-	elif opt in ("-m", "--mmult"):
+        elif opt in ("-m", "--mmult"):
 	            mmult = int(arg)
 
 
     if (infile != '' and out != '' and take !=0):
         compute(infile,out,comp,take,bits,mmult)
     else:
-        print "\nYou must provide input, output files and number of particles to take.....\n\n"
+        print ("\nYou must provide input, output files and number of particles to take.....\n\n")
         printHelp(prog)
         
 # - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -233,7 +234,7 @@ def printHelp(prog):
         mmult      : multiply mass by take (default 1 - yes,  else  0 -  no)
 
     """
-    print help % (prog,prog)
+    print (help % (prog,prog))
         
 # - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 # main