diff --git a/pymath/calculus/equation.py b/pymath/calculus/equation.py
index b03d95e..dee4cb2 100644
--- a/pymath/calculus/equation.py
+++ b/pymath/calculus/equation.py
@@ -14,19 +14,24 @@ __all__ = ['Equation']
 class Equation(object):
     """A calculus expression. Today it can andle only expression with numbers later it will be able to manipulate unknown"""
 
-#    @classmethod
-#    def random(self, form="", conditions=[], val_min=-10, val_max=10):
-#        """Create a random expression from form and with conditions
-#
-#        :param form: the form of the expression (/!\ variables need to be in brackets {})
-#        :param conditions: condition on variables (/!\ variables need to be in brackets {})
-#        :param val_min: min value for generate variables
-#        :param val_max: max value for generate variables
-#
-#        """
-#        random_generator = RdExpression(form, conditions)
-#        return Expression(random_generator(val_min, val_max))
-#
+    @classmethod
+    def random(self, form="", conditions=[], val_min=-10, val_max=10):
+        """Create a random expression from form and with conditions
+
+        :param form: the form of the expression (/!\ variables need to be in brackets {})
+        :param conditions: condition on variables (/!\ variables need to be in brackets {})
+        :param val_min: min value for generate variables
+        :param val_max: max value for generate variables
+
+        >>> Equation.random("{a}x + {b} = 0") # doctest:+ELLIPSIS
+        < Equation [..., 0]>
+        >>> Equation.random("{a}x + {b} = _", conditions = ["{a}==2"]) # doctest:+ELLIPSIS
+        < Equation [2 x ...]>
+
+        """
+        random_generator = RdExpression(form, conditions)
+        return Equation(random_generator(val_min, val_max))
+
 
     def __init__(self, exp_str = "", left_poly = Expression([0]), right_poly = Expression([0])):
         """Create the equation