Dear Monks,

I'm not sure how I can understand the output I'm getting from the sample program below. Maybe (probably) something quite simple that I'm missing..
I need to calculate square roots with more than the standard precision so I'm using use bignum. This works fine unless it is in a loop. Anybody care to explain? 
use strict;
use warnings;

use Data::Dumper;
use bignum(a=>200);

my $s = sqrt(2);;
print Dumper(\$s);

for my $num (2..2) {
    $s = sqrt($num);
    print Dumper(\$s);
}

[download]
The output is: 
$VAR1 = \bless( {
                   '_es' => '-',
                   '_m' => [
                             605715,
                             1152782,
                             9995050,
                             5927557,
                             5927505,
                             1322266,
                             9358314,
                             1497099,
                             1264412,
                             8507372,
                             4836055,
                             9702492,
                             2309122,
                             5013846,
                             4157273,
                             5343276,
                             8850387,
                             6210703,
                             7324784,
                             9737990,
                             7317667,
                             3769480,
                             9671875,
                             9807856,
                             7242096,
                             8801688,
                             7309504,
                             2135623,
                             1414
                           ],
                   '_a' => 200,
                   '_e' => [
                             199
                           ],
                   'sign' => '+'
                 }, 'Math::BigFloat' );
$VAR1 = \'1.4142135623731';

[download]
It looks as if the blessing of $s is lost in the loop, but I don't understand why.
si_lence (confused)
Update: Thanks everybody for pointing out the reason and the suggestions. I did read the documentation, but obviously glossed over the important part.

In reply to 'use bignum' scoping question by si_lence

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