Hi Roger,
Thanks a lot for the feedback and useful criticism.

> 1) Add use strict; to the beginning of your code to prevent autovivification of variables.

Yes, by the time I posted it here I had already used strict everywhere. Initially I had error messagse that I could not understand but eventually got over.

> Do this instead: my $SOME_GLOBAL_VARIABLE=some_sub_without_side_effects();

You are right. But the way I needed to use was to have several variables to be returned, which would be easier with global variables than with several functions. :)

> 3) Remove the { } around the function calls, they are unnecessary and ugly.

I was intending to use eval... In retrospect, that was not required. Yes, I would be removing them now. :)

> 4) Use IO::File ...

Yes, I would be using it from now on. Thanks. :)

> 5) When modifying a Perl built-in variable, always create a scope and localize it first...

This has been a problem for me to understand, I need better books for advanced settings. I am not sure which are actually global and which are not.

My array sizes are huge so I was not sure if I should use subroutines which might duplicate all the variables upon passing the info, but I could not verify if it actually happens. These problems exists, but I could somehow write my first code.

> Anyway, good luck and happy Perl programming.

Thanks. It's been an ugly code, but I am happy to have shfted from FORTRAN for these things. :)

Sorry I could not reply earlier, was out for some trip.

Thanks a lot again. :)