Can't calculate the Fibonacci number, there is someone strong on this issue?

Question

Can't calculate the Fibonacci number, there is someone strong on this issue?

Is not so much to calculate how many you want to understand how it is calculated.
Task: Implement a function fib which Fibonacci numbers. A function argument is the ordinal number.
f(0) = 0
f(1) = 1
f(n) = f(n-1) + f(n-2)

Example:
2 == fib(3) // if formula then there must be fib(3) = f(n-1) + f(n-2) = f(2) + f(1) = 2+1=3, how 2 got ???
5 == fib(5) // then what is 5 ???
55 == fib(10)

jeremy.Stamm asked July 9th 19 at 11:19

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More answers about "Can't calculate the Fibonacci number, there is someone strong on this issue?"

3 answers

Daphne_Roob answered on July 9th 19 at 11:23

You need to learn the concept of recursion.
"2 as it turned out" - as f(2) = f(n-1) + f(n-2)
Only you have the error, fib(3) = 2 and not 3
Code codepen.io/anon/pen/ezOxMQ?editors=1111

nicklaus.Will answered on July 9th 19 at 11:25

Apparently the problem is in Your function, try:

function fibonacci($n)
{
 if ($n < 3) {
 return 1; 
}
 else {
 return fibonacci($n-1) + fibonacci($n-2);
}
}

for ($n = 1; $n <= 16; $n++) {
 echo(fibonacci($n) . ", ");
}
echo("...\n")

progopedia.ru/example/fibonacci/89

odell_Nol answered on · Accepted Answer · 2019-07-09T11:21:50.511Z

odell_Nol answered on July 9th 19 at 11:21

Solution

f(2) = f(1) + f(0) = 1. Here's where you went wrong. So

f(3) = f(2) + f(1) = 1 + 1 = 2;
f(4) = f(3) + f(2) = 2 + 1 = 3;
f(5) = f(4) + f(3) = 3 + 2 = 5;
f(6) = f(5) + f(4) = 5 + 3 = 8;
f(7) = f(6) + f(5) = 8 + 5 = 13;