Fibonacci with recursion method

Question

I am trying to implement a fibonacci function that should takes as input 3 arguments, r = the number of the output elements, 'a' the start number and 'b' the second number. fib(r,a,b)

I have done the following but something goes wrong:

def fib(r,a,b):
    return [[(a,b),fib(i,b,a+b)] for i in range(r)]

Can anyone said me where is the problem and help me to solve it?

Side note: if this is python 2 range(SOME_BIG_NUMBER) will actually create a list with many numbers inside before doing anything. — Reut Sharabani
– Reut Sharabani, Commented Oct 27, 2015 at 23:12
What is the desired output? As it is, even if you fix the errors, you will get lists inside lists — Pynchia
– Pynchia, Commented Oct 27, 2015 at 23:15
the function is called fib and inside it calls fib (refers to itself) — Adrienne
– Adrienne, Commented Oct 27, 2015 at 23:15
Please change your question containing the desired and the actual output. Putting that in comments is not such a good idea. — Alfe
– Alfe, Commented Oct 27, 2015 at 23:17

L3viathan · Accepted Answer · 2015-10-27 23:25:48Z

2

You're calling the function within the list comprehension, making the lists recursive. Also, you're missing a condition under which the function terminates.

Try this instead:

def fib(r,a,b):
    return [a] + fib(r-1,b,a+b) if r>0 else []

Note that this is horribly inefficient and should never be actually used.

answered Oct 27, 2015 at 23:25

L3viathan

27.5k2 gold badges63 silver badges84 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

usr9 Over a year ago

ok i have understand, but i cant to do it like this because i can concatenate list with list not number with list. is it right?

L3viathan Over a year ago

Correct, that's why you concatenate a list with a list here! a is a number, but [a] is a list!

Collectives™ on Stack Overflow

Fibonacci with recursion method

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related