You can try sorting the float values within the array by using something like:
float $list[]={65.4, 0.2, 5.2, 10.6, 1.7};
$list = sort $list;
Then by accessing the first or last element of the array you can have the smallest or largest float within it respectivelly:
print ("\nLargest float: " + ($list[size ($list )-1]));
print ("\nSmallest float: " + ($list[0]));