$x = f( $o->next ) + g( $o->next );
$y = f( $o->next ) - g( $o->next );

##</code><code>##

$x =  g( $o->next ) + f( $o->next );
$y = -g( $o->next ) + f( $o->next );

##</code><code>##

my $temp1 = $o->next;
my $temp2 = $o->next;
$x = f( $temp1 ) + g( $temp2 );

$temp1 = $o->next;
$temp2 = $o->next;
$y = g( $temp1 ) - f( $temp2 );

##</code><code>##

my $temp1 = $o->next;
my $temp2 = $o->next;
$x = f( $temp2 ) + g( $temp1 );

$temp1 = $o->next;
$temp2 = $o->next;
$y = f( $temp1 ) - g( $temp2 );