Hi again 1nickt,
Following your advise, I'm now attempting to transform the secondary script, compute.pl, as a single subroutine and make this script exporting the necessary variable and of course its subroutine. If I can achieve this by applying little modifications to it, then it solves my problem in what I believe to be an elegant way.

Since this script was meant to be executed as "perl compute.pl -arg1 arg2 (...) arg10 input_file > output_file", I need to find a corresponding syntax for the file input and output when calling the subroutine.
Exporting variable and subroutine from one script to another is ok, I know how to proceed :)

Thanks again for guiding me in what looks to be the right direction :)