my $x = 0.05;
my $y = sqrt($x+$x+$x);
my $g = "$y";
my $h = sprintf "%.20f", $y;

printf "\$y = %.20f\n\$g = %.20f\n", $y, $g;
printf "\$h = %.20f\n", $h;
print "Is \$y equal to \$g? ", floatEqual($y, $g) ? "Yes\n" : "No\n";
print "Is \$y equal to \$h? ", $y == $h ? "Yes\n" : "No\n";

sub floatEqual {
    return (abs($_[0] - $_[1]) <= 10**15);
}