Conditional statement traces
============================

You can solve this exercises manually. Then you can check your answers
using a Python shell or the `Online python tutor
<http://www.pythontutor.com/>`__ tool.

#. Write the trace of this function. Could it be simplified ?. How ?

   .. code:: python

     def f1(a):
       if a > 0 :
          b = a - a
       elif a < 0 :
          b = -a + a
       else :
          b = 0
       c = a - b
       a = a - c
       return a, b, c

#. Write the trace of this function.

   .. code:: python

     def f2(a):
       if a > 0 :
          b = -a
       else :
          b = a
       c = a - b
       h = c == 0 or c > 0
       return b, c, h

#. Which is the value returned by the following function for these
   calls: ``f3(7)``, ``f3(20)``, ``f3(-36)``, ``f3(36)`` and ``f3(9)`` ?

   .. code:: python

    def f3(a): 
        if a > 0 :
            if a%2 == 0:
                if a%3 == 0 :
                    b = a + 6
                else: 
                    b = a + 2
            else :
                b = 6
        else :
            b = 0
        return b

#. Discuss whether or not the following functions ``f4`` and ``f5`` return
   the same value for all possible values of ``x`` and ``y``.

   .. code:: python
	     
    def f4 (x, y):
        if x == y:
            z = 0
        elif x < y:
            z = -1
        else:
            z = 1
        return z

    def f5 (x, y):
        if x == y:
            z = 0
        if x < y:
            z = -1
        else:
            z = 1
        return z