Here's a sample program that uses Math::BigFloat to compute square roots with the Newton-Raphson method. It will compute the square root of the argument you give it, 2 by default.

use Math::BigFloat;

my $N = shift || 2;
$g = Math::BigFloat->new($N);

for (;;) {
  $g = ($g + ($N/$g))/2;
  print $g, "\n";
}
[download]

This is just a demonstration. Normally, a programmer using Math::BigFloat would use the ->fsqrt method to extract a square root.