Find value from the while loop

[vivis933]

<?php
function factorial($number)
{
if ($number < 2) {
return 1;
} else {
return ($number * factorial($number-1));
}
}

function poisson($occurrence,$chance)
{
$e = exp(1);

$a = pow($e, (-1 * $chance));
$b = pow($chance,$occurrence);
$c = factorial($occurrence);

return $a * $b / $c;
}

$x = 2.5;
$y = 1.5;
$calAll = array();
for($z = 0 ; $z <= 9 ; $z++) {
array_push($calAll,
(poisson($z,$x) * poisson(0,$y))*100,
(poisson($z,$x) * poisson(1,$y))*100,
(poisson($z,$x) * poisson(2,$y))*100


);
}
$value = max($calAll);
$key = array_search($value, $calAll);
print_r($calAll) . "\n";
echo "max =",$value , " key =",$key . "\n";;
?>

it is possible to find $z and the number 0,1 or 2 from the max of the returned array ?

I used excel to perform this action and i found that for max=8.5854557290941 the $z is 2 and number 1 how to achieve this in php ?