Fibonacci sequence

[Darbandiman123]

Hey i have this code which should print out fibonaccis sequence yet encounter the following error.

Error:
Traceback (most recent call last):
  File "C:\Users\Louis\csyr9\fibonacci.py", line 12, in <module>
    fibonacci()
  File "C:\Users\Louis\csyr9\fibonacci.py", line 5, in fibonacci
    while a <= 20:
UnboundLocalError: local variable 'a' referenced before assignment

here is the code:

a = 1
b = 2

def fibonacci():
    while a <= 20:
        c = a+b
        d = b+c
        print (a,b,c,d)
        a = c
        b = d
fibonacci()

how do i fix this? thanks

[ichabod801]

You need to define a and b in the function (indented under def fibonacci). Since you assign a value to a within the function, it assumes that variable is local to the function. Then it doesn't look outside the function for the value. But then on line 5 it can't find the value of a, since it hasn't been defined in the function.

See the function tutorial link in my signature below for more information.

[Darbandiman123]

Thanks!