PHP 斐波那契数列

Question

此 php 方法假设使用 for 循环打印斐波那契数列直到指定值。我不确定为什么它不起作用？

<?php
function fib ($n) { // a function called fib, declaire variable n (the sequence number)
    for ($n=0;$n<30;$n++) {
        if ($n < 3) { return $n; } // if n is smaller than 3 return n (1 or 2)
        else { return fib ($n - 1) + fib ($n - 2); } 
    /* if the number is 3 or above do 2 sums (n-1) and (n-2)
    and then add the 2 sums together (n-1)+(n-2)
    Example Fibonacci number 4
    (4-1)+(4-2) = 5
    3 + 2 = 5
    */
}
print $n;
?>

Answer 1

实际上有一种方法可以通过四舍五入来计算斐波那契数而无需迭代:

http://en.wikipedia.org/wiki/Fibonacci_number#Computation_by_rounding

function getFib($n)
{
    return round(pow((sqrt(5)+1)/2, $n) / sqrt(5));
}