Fibonacci sequence with index of first term to contain 1000 digits

Fibonacci.php

<?php
// Function to generate fibonacci sequence that contains large numbers
    function getFibonacci() {
        $i = '0';
        $k = '1'; //first fibonacci value
        yield $k;
        while(true) {
            // gmp_add to add two gmp number (www.php.net/manual/en/ref.gmp.php)
            $k = gmp_add($i, $k);
            // gmp_subtract to subtract $i from $k
            $i = gmp_sub($k, $i);
            yield $k;
        }
    }
    /*
     * This function finds and print the first fibonacci sequence number
     * with 1000 digits
     */
    function getFab1()
    {
        //  fibonacci series from getFibonacci2()
        foreach(getFibonacci() as $value) {
            // Function breaks with the first 1000 digits
            if (strlen($value) == 1000) {
                break;
            }
        }
        // prints the value
        echo $value, PHP_EOL;
    }
    /*
     * This function prints fibonacci sequence starting from
     * digits 1000 $n number of times
     */
    function Fibonacci($n)
    {
      
        // Initialize first and second number to 0 and 1
            $num1 = 0;
            $num2 = 1;
            // initialize counter and set to 0
            $counter = 0;
            // send the flow to iterative while loo[ where we get the next number
            // that starts with 1000 digits and adding the previous two number
            // and simultaneously we swap the first number with the second, and second
            // with third
            while ((strlen($num1) >= strlen(getFab1())) && ($counter < $n)){
                echo ' '.$num1;
                $num3 = $num2 + $num1;
                $num1 = $num2;
                $num2 = $num3;
                $counter = $counter + 1;
            }
    }
    /*
     * This sets and runs fibonacci sequence with index of the first term to contain 1000 digits
     */
   
        $n = 10;
        Fibonacci($n);
?>