php - Fibonacci series optimisation

How can i optimise this ? Am getting timeout error when i executes this I am trying to execute this on my wampserver on a windows 10. This code is actually that i wrote for a test but the test fails if i get the values of $a and $b as huge.

Any help will be welcome. Thank you.

     * @param $n
     * @param false $offset
     * @param false $injectResult
     * @return int|mixed
     */

Seems that this part is the worm

function fibonacci($n, $offset = false, $injectResult = false)
{
    if ($offset == $n && $injectResult) {
        return $injectResult;
    }
    if ($n == 0) {
        return 0;
    }
    if ($n == 1) {
        return 1;
    }
    if ($n > 1) {
        return fibonacci($n - 1) + fibonacci($n - 2);
    }
}

    /**
     * Function to sum the fibonacci series result
     * @param $a
     * @param $b
     * @return float|int
     */

This part seems ok

function sumFibonacci($a, $b)
{
   $diff = $b - $a;
   $result = [];
   for ($i = 0; $i <= $diff; $i++) {
       if ($i == 0) {
           $result[$i] = fibonacci($a);
       } else {
           $result[$i] = fibonacci($a + $i, $a - ($i - 1), $result[$i - 1]);
       }
   }
       return array_sum($result);
}
// Example of how to use it
echo sumFibonacci(38,58);

/**
* How can i optimise this if  $a = 38 $b= 58 e.g sumFibonacci(38,58);
*/ ```

   

Solution:

I solved it by modified the function to be non recursive

{
    $numnar1 = 0;
    $numnar2 = 1;
    $count = 0;
    $result='';
    while ($count < $numnar) {
        $result =  $numnar1;
        $numnar3 = $numnar2 + $numnar1;
        $numnar1 = $numnar2;
        $numnar2 = $numnar3;
        $count++;
    }
    return $result;
}