sub srs_full_matrix {
    my $mov = shift;
    my $played = shift;
    my $opt = shift || ();
    my $epsilon =  0.001;
    my $maxiter =  1000000;
    my $debug = 0;
    $epsilon = $opt->{epsilon} if ( $opt->{epsilon} );
    $maxiter = $opt->{maxiter} if ( $opt->{maxiter} );
    $debug = $opt->{debug} if ( $opt->{debug} );
    my $srs = $mov->copy();
    my $oldsrs = $srs->copy();
    my $delta = 10.0;
    my $iter = 0;
    while ( $delta > $epsilon and $iter < $maxiter ) {
        my $wt = 1.0 / sumover $played;
        my $prod = $srs x $played;
        my $sos  = $wt * $prod;
        $srs = $mov + $sos;
        $delta = max abs ( $srs - $oldsrs );
        $oldsrs = $srs->copy();
        $iter++;
    }
    print "iter  = $iter\n" if $debug;
    print "epsilon  = $epsilon\n" if $debug;
    printf "delta = %7.4f\n", $delta if $debug;
    my $offset = sum $srs;
    $srs -= ( $offset / $mov->nelem );
    return $srs->slice(":,(0)");
}


##</code><code>##

sub load_srs_data {
    my $games = shift;
    my %team;
    for ( @$games ) {
        my ( $visitor, $visit_score, $home_team, $home_score ) = split "\,", $_;
        my $diff = $home_score - $visit_score;
        $team{$visitor}{games_played}++;
        $team{$home_team}{games_played}++;
        $team{$visitor}{points} -= $diff;
        $team{$home_team}{points} += $diff;
        push @{$team{$visitor}{played}}, $home_team;
        push @{$team{$home_team}{played}}, $visitor;
    }
    my $total_team = scalar keys %team;
    my $played = zeroes $total_team, $total_team;
    my $mov = zeroes $total_team;
    my %team_map;
    my $ii = 0;
    for ( sort keys %team ) {
        my $team_diff = $team{$_}{points} / $team{$_}{games_played};
        $team_map{$_} = $ii;
        $mov->set( $ii, $team_diff );
        $ii++;
    }
    for ( keys %team ) {
        my $i = $team_map{$_};
        for my $opp (@{$team{$_}{played}}) {
            my $j = $team_map{$opp};
            my $a = $played->at ( $i, $j );
            $a++;
            $played->set( $i, $j, $a );
        }
    }
    return \%team, \%team_map, $mov, $played;
}