Optimize the sech²(x) function a bit.

[foosball] / recalc-single-result.pl

diff --git a/recalc-single-result.pl b/recalc-single-result.pl
index 02f421b899b5bef903db0074abe8ba3a2d13d5e2..679478791027ecb283f9ea6a88028b9ac8fc3d19 100755 (executable)
--- a/recalc-single-result.pl
+++ b/recalc-single-result.pl
@@ -15,6 +15,9 @@ my %ratings = ();
 my $q = $dbh->prepare('select *,extract(epoch from gametime) as eptime from single_results order by gametime');
 $q->execute;
 
+# Combined log-likelihood
+my $cll = 0.0;
+
 while (my $ref = $q->fetchrow_hashref) {
        for my $user (($ref->{'username1'}, $ref->{'username2'})) {
                if (!exists($ratings{$user})) {
@@ -36,16 +39,18 @@ while (my $ref = $q->fetchrow_hashref) {
        $rd1 = foosball::apply_aging($rd1, $age1 / 86400.0);
        $rd2 = foosball::apply_aging($rd2, $age2 / 86400.0);
 
-       my ($newr1, $newrd1) = foosball::calc_rating($rating1, $rd1, $rating2, $rd2, $score1, $score2);
+       my ($newr1, $newrd1, $likelihood) = foosball::calc_rating($rating1, $rd1, $rating2, $rd2, $score1, $score2);
        my ($newr2, $newrd2) = foosball::calc_rating($rating2, $rd2, $rating1, $rd1, $score2, $score1);
 
-       printf("%-10s - %-10s: %u - %u, new ratings %u/%u %u/%u\n",
+       $cll += log($likelihood);
+
+       printf("%-10s - %-10s: %u - %u, new ratings %u/%u %u/%u [$likelihood]\n",
                $ref->{'username1'}, $ref->{'username2'}, $ref->{'score1'},
                $ref->{'score2'}, $newr1, $newrd1, $newr2, $newrd2);
-       $dbh->do('insert into single_rating values (?,?,?,?)', undef,
-               $ref->{'username1'}, $ref->{'gametime'}, $newr1, $newrd1);
-       $dbh->do('insert into single_rating values (?,?,?,?)', undef,
-               $ref->{'username2'}, $ref->{'gametime'}, $newr2, $newrd2);
+       $dbh->do('insert into single_rating values (?,?,?,?,?)', undef,
+               $ref->{'username1'}, $ref->{'gametime'}, $newr1, $newrd1, $newr1-$rating1);
+       $dbh->do('insert into single_rating values (?,?,?,?,?)', undef,
+               $ref->{'username2'}, $ref->{'gametime'}, $newr2, $newrd2, $newr2-$rating2);
 
        $ratings{$ref->{'username1'}} = [ $newr1, $newrd1, $ref->{'eptime'} ];
        $ratings{$ref->{'username2'}} = [ $newr2, $newrd2, $ref->{'eptime'} ];
@@ -53,3 +58,6 @@ while (my $ref = $q->fetchrow_hashref) {
 
 $dbh->commit;
 $dbh->disconnect;
+
+printf "\nCombined negative log-likelihood (smaller value means a better model): %f\n",
+       -$cll;