Problem 1997. Compute Fibonacci Number

This is cool because there's also an explicit equation (Binet) for this!

While this is one way of doing it, this solution uses built-in fibonacci function.

There is no built-in fibonacci function. The existing function is a part of the symbolic toolbox and isn't available on Cody.

This code uses recursion on the main function fibonacci.

However, this is also a cheat solution, using regexp to limit the solution size. If you see other solutions like this, please report them using the flag button.

This solution returns f(0) = 1, which contradicts the decription of the given problem.

This solution uses filter from the Signal Processing Toolbox.

Yes, it uses filter, but filter is indeed not a toolbox function, but a built-in function. You can fix the error by changing f=y(n-2) to f = y(n)

... and then change first input of filter to [1,-1] and remove +1 from the end of the line.

Test suite is flawed. I had to add a round(x,0) function to the output to make it pass.

Test is correct. Fibonacci Numbers are integers, so your output should be to.