Hi again, cool,

You still have uninitialized variables (eg. "dinu_r").  Besides that, I don't know what your input file looks like.

But perhaps this will help to give you an idea about what the other monks are strongly suggesting; namely, that you use a better data structure (eg. a hash of arrays) instead of symbolic references:

# Near the top of the code
my %energy;

# Later on ...
    foreach my $el1(sort{$a <=> $b} keys %Winenergy) {
        #  push(@energy.$x , $Winenergy{$el1});    #LINE C
        #  print OUT "$el1\t $Winenergy{$el1}\n";

        $energy{"energy$x"} ||= [ ];                    # Initialize a
+rray ref
        push @{$energy{"energy$x"}}, $Winenergy{$el1};  # Save to appr
+opriate array
    }
[download]

Does that help you to get started?