#!perl -w
use strict;
use Data::Dumper;

sub get_SAS {
    my ($ini,$last) = @_;
    my %result=(
        SAS1=>$ini-$last, # 2
        SAS2=>$last-$ini, # -2
        SAS3=>$ini-$last  # 2
    );
    return %result
};

my %res42 = get_SAS(4,2);
print Dumper \%res42;
my %res105 = get_SAS(10,5);
print Dumper \%res105;
__END__
$VAR1 = {
          'SAS3' => 2,
          'SAS2' => -2,
          'SAS1' => 2
        };
$VAR1 = {
          'SAS3' => 5,
          'SAS2' => -5,
          'SAS1' => 5
        };