Problem 2982. Get a Fibonacci number's index.
N.B. For the purpose of this exercise, the first Fibonacci number is 1, and the second is 2; that is, fib(1) = 1 and fib(2) = 2 .
Make a function isfib(x) so that:
- if the value of the input x is not a Fibonacci number, the function returns a zero.
- if the value of the input x is a Fibonacci number, the function returns its index in the Fibonacci sequence. That is, isfib(fib(n)) should return the value of n .
Solution Stats
Problem Comments
-
2 Comments
5.731478440138172e+20 from 7th test is not a Fibonacci Number. 100th Fibonacci Number in proposed convention is 573147844013817084101 which has 21 digits and exceeds double precision.
I agree with Jan. http://www.maths.surrey.ac.uk/hosted-sites/R.Knott/Fibonacci/fibtable.html (this list begins at 0). The 100th fibonnaci number is 573147844013817084101 (5.731478440138171e+20), and not 5.731478440138172e+20.
Solution Comments
Show commentsProblem Recent Solvers44
Suggested Problems
-
Flip the main diagonal of a matrix
787 Solvers
-
We love vectorized solutions. Problem 1 : remove the row average.
810 Solvers
-
719 Solvers
-
1523 Solvers
-
Approximation of Pi (vector inputs)
202 Solvers
Problem Tags
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!