use strict;
use warnings;
use diagnostics;

#main()
{
   my @data = ([0.11,0.07,0.19],
               [0.43,0.31,0.37],
               [0.95,0.78,0.82],
               [0.91,0.12,0.15],
               [0.52,0.18,0.32]);

    foreach (@data){
       my $pval = P($_);
       print "value = $pval\n";
    }
    exit;
} #end main()


sub P{
    my $data = shift;
    my $n = @{$data};
    my $rslt1 = 0;
    my $rslt2 = 0;
    my $rslt  = 0;
    
    return $$data[0] if($n == 1);    #r(0) = 0 ==> r(1)-r(0) = r(1)
                                     #assume P(r(0)) = 1
    unshift @{$data}, 0;

    for(my $i=1;$i <= $n; $i++){
        my @nextdata = ();
        for (1..$n){
            next if($_ == ($n-$i+1));
            push @nextdata, $$data[$_];
        }
                                    # split up rslt1 & 2 for clarity
        $rslt1 = ($$data[$n-$i+1] - $$data[$n-$i]);
        $rslt2 = P(\@nextdata);
        $rslt  += $rslt1 * $rslt2;
    }
    return $rslt;
}

__DATA__
value = 0.001595
value = 0.046225
value = 0.549005
value = 0.439894
value = 0.010192