Unpacking features in more user friendly format

Hey,

I read GIFT literature and I have an idea of what GIFT does and what I can 
expect from GIFT. Using Perl script, I am trying to unpack the .fts files so I 
can see featureID and their frequencies. I used the script from Dr. Muller 
with small modification so I can sort features in ascending order but I am 
wary of accepting the result.

Here is my my script:

       open (FILE,shift)|| die "can't open the file $file";
       %features= ();
       read (FILE,$lString,4) || die ("Cannot read the file $file");
         while (read FILE,$lString,8|| die ("Cannot read the file $file")){
         my ($FeatureID,$Frequency)=unpack("If",$lString);
               if ($Frequency>0){
               $features{"$FeatureID"}=$Frequency;
                                }
         }
  
        foreach $key (sort{$a<=>$b} keys %features){
              print "$key:$features{$key}";}

My output seems to have some big numbers both in FeatureID and Frequencies and 
I am wondering if this is accurate or something went wrong during features 
extraction.
Here is an example of some of the features form one .fts file:

0:3.48554469996741e+28
1006665857:1.22526735123633e-40
4181688320:2.15799963506022e-43
4215242752:1.82168800362226e-43

I would appreciate some help or advice on how to convert the .fts into a more 
user friendly because I am questioning these bif numbers in my output.

Thank you very much

Epa Uwimana