I need help with this trivial function.

I'm trying to run this script but I keep getting this error mensage:

          ??? Input argument "x" is undefined.

          Error in ==> fibonacci at 8

Could anybody help me? Here is the code:

function y = fibonacci(x)
if x == 0
    y = 0
elseif x == 1
    y = 1
else
    y = fibonacci(x-1) + fibonacci(x-2)
end

[Roger Stafford]

It should be pointed out that evaluating the Fibonacci series using this kind of recursion is particularly inefficient. The number of recursive calls on the function for an argument value of x would be even greater than the corresponding Fibonacci value at x, which is to say that it increases exponentially in x.

[Jan]

@Roger: Exactly. And this is the cause, why Fibonacci is such a famous example for learning how to apply recursive programming and why to avoid it. See also: http://www.mathworks.com/matlabcentral/answers/2346-hump-day-challenger-recursion

Answer 1

[Dishant Arora]

This isn't a script, it's a function. You need to pass input argument while calling the function.

x = 4 ;
y = fibonacci(4) or fibonacci(x);