diff --git a/expression.py b/expression.py
index c268135..563e1cd 100644
--- a/expression.py
+++ b/expression.py
@@ -3,7 +3,7 @@
 
 from generic import Stack, flatten_list, expand_list
 from fraction import Fraction
-from render import txt_render, post2in_fix, tex_render
+from renders import txt_render, post2in_fix, tex_render
 from formal import FormalExp
 from formal import FormalExp
 
diff --git a/random_expression.py b/random_expression.py
index 2a81215..7007226 100644
--- a/random_expression.py
+++ b/random_expression.py
@@ -3,6 +3,7 @@
 
 from random import randint
 from expression import Expression
+from renders import tex_render, txt_render
 import re
 
 class RdExpression(object):
@@ -49,23 +50,13 @@ class RdExpression(object):
         return varia
 
 
-    def __call__(self, val_min = -10, val_max = 10):
+    def __call__(self, val_min = -10, val_max = 10, render = tex_render):
         """RdExpression once it is initiate act like a function which create random expressions.
 
         :param val_min: minimum value random generation
         :param val_max: maximum value random generation
-        :returns: an random expression formated for console printing
-
-        """
-        return str(self.raw_exp(val_min, val_max))
-
-    def render(self, val_min = -10, val_max = 10, render = lambda x: str(x)):
-        """Same as __call_ but uses render from the Expression object
-
-        :param val_min: minimum value random generation
-        :param val_max: maximum value random generation
-        :param render: function which render the list of token (postfix form) to string
-        :returns: an random expression formated by render
+        :param render: Render of the expression (returns an Expression by default)
+        :returns: an formated random expression 
 
         """
         return render(self.raw_exp(val_min, val_max).postfix_tokens)
@@ -108,13 +99,13 @@ class RdExpression(object):
             return True
 
 def desc_rdExp(rdExp):
-    from render import tex_render
+    from renders import tex_render
     print("--------------------")
     print("form: ",rdExp._form)
     print("Conditions: ",rdExp._conditions)
     print("Letters: ", rdExp._letters)
     print("2replaced: ", rdExp._2replaced)
-    print("Call : ", rdExp.render(render = tex_render))
+    print("Call : ", rdExp(render = tex_render))
     print("Gene varia: ", rdExp._gene_varia)
     print("Gene 2replaced: ", rdExp._gene_2replaced)
     print('')
diff --git a/render.py b/render.py
index a93112f..c3c872b 100644
--- a/render.py
+++ b/render.py
@@ -5,8 +5,6 @@ from generic import Stack,flatten_list
 from fraction import Fraction
 from formal import FormalExp
 
-        
-
 class Render(object):
     """A class which aims to create render functions from three dictionnaries:
         - op_infix: dict of caracters
@@ -201,53 +199,6 @@ class flist(list):
     pass
 
 
-# ------------------------
-# A console render
-
-txt_infix = {"+": "+", "-": "-", "*": "*", "/" : "/", ":": ":"}
-txt_postfix = {}
-txt_other = {"(": "(", ")": ")"}
-
-txt_render = Render(txt_infix, txt_postfix, txt_other)
-
-# ------------------------
-# A infix to postfix list convertor
-
-p2i_infix = {"+": "+", "-": "-", "*": "*", "/" : "/", ":":":"}
-p2i_postfix = {}
-p2i_other = {"(": "(", ")": ")"}
-
-post2in_fix = Render(p2i_infix, p2i_postfix, p2i_other, join = False)
-
-# ------------------------
-# A latex render
-
-def texSlash(op1, op2):
-    if not Render.isNumerande(op1) and op1[0] == "(" and op1[-1] == ")":
-        op1 = op1[1:-1]
-    if not Render.isNumerande(op2) and op2[0] == "(" and op2[-1] == ")":
-        op2 = op2[1:-1]
-    return ["\\frac{" , op1 , "}{" , op2 , "}"]
-
-def texFrac(frac):
-    return ["\\frac{" , str(frac._num) , "}{" , str(frac._denom) , "}"]
-
-tex_infix = {"+": " + ", "-": " - ", "*": " \\times ", ":": ":"}
-tex_postfix = {"/": texSlash}
-tex_other = {"(": "(", ")": ")"}
-tex_type_render = {int: str, Fraction: texFrac, FormalExp: str}
-
-tex_render = Render(tex_infix, tex_postfix, tex_other, type_render = tex_type_render)
-
-
-
-if __name__ == '__main__':
-    exp = [2, 5, '+', 1, '-', 3, 4, '*', ':']
-    print(txt_render(exp))
-    exp = [2, 5, '+', 1, '-', 3, 4, '*', '/', 3, 5, '/', ':']
-    print(tex_render(exp))
-    exp = [2, 5, '+', 1, '-', 3, 4, '*', '/', 3, '+']
-    print(post2in_fix(exp))
     
 # -----------------------------
 # Reglages pour 'vim'
diff --git a/renders.py b/renders.py
new file mode 100644
index 0000000..51db589
--- /dev/null
+++ b/renders.py
@@ -0,0 +1,62 @@
+#!/usr/bin/env python
+# encoding: utf-8
+
+from render import Render
+from fraction import Fraction
+from formal import FormalExp
+
+# ------------------------
+# A console render
+
+txt_infix = {"+": "+", "-": "-", "*": "*", "/" : "/", ":": ":"}
+txt_postfix = {}
+txt_other = {"(": "(", ")": ")"}
+
+txt_render = Render(txt_infix, txt_postfix, txt_other)
+
+# ------------------------
+# A infix to postfix list convertor
+
+p2i_infix = {"+": "+", "-": "-", "*": "*", "/" : "/", ":":":"}
+p2i_postfix = {}
+p2i_other = {"(": "(", ")": ")"}
+
+post2in_fix = Render(p2i_infix, p2i_postfix, p2i_other, join = False)
+
+# ------------------------
+# A latex render
+
+def texSlash(op1, op2):
+    if not Render.isNumerande(op1) and op1[0] == "(" and op1[-1] == ")":
+        op1 = op1[1:-1]
+    if not Render.isNumerande(op2) and op2[0] == "(" and op2[-1] == ")":
+        op2 = op2[1:-1]
+    return ["\\frac{" , op1 , "}{" , op2 , "}"]
+
+def texFrac(frac):
+    return ["\\frac{" , str(frac._num) , "}{" , str(frac._denom) , "}"]
+
+tex_infix = {"+": " + ", "-": " - ", "*": " \\times ", ":": ":"}
+tex_postfix = {"/": texSlash}
+tex_other = {"(": "(", ")": ")"}
+tex_type_render = {int: str, Fraction: texFrac, FormalExp: str}
+
+tex_render = Render(tex_infix, tex_postfix, tex_other, type_render = tex_type_render)
+
+
+
+if __name__ == '__main__':
+    exp = [2, 5, '+', 1, '-', 3, 4, '*', ':']
+    print(txt_render(exp))
+    exp = [2, 5, '+', 1, '-', 3, 4, '*', '/', 3, 5, '/', ':']
+    print(tex_render(exp))
+    exp = [2, 5, '+', 1, '-', 3, 4, '*', '/', 3, '+']
+    print(post2in_fix(exp))
+
+
+
+
+# -----------------------------
+# Reglages pour 'vim'
+# vim:set autoindent expandtab tabstop=4 shiftwidth=4:
+# cursor: 16 del