use Math::BigFloat;

my $one_minus_one = Math::BigInt->new(1) - Math::BigFloat->new(.9999);
print "$one_minus_one\n";

##</code><code>##

#!perl
use bignum;

my $tmp = "-0.00000000000000007573064690121714";
my $e = exp($tmp);

printf("%3.20g\n", $e);
print "$e ", 1-$e, "\n";