...

// Find current user's (karma giver's) "karma power"
      // this is an arbitrary kind of calculation.  Long time members, or members of
      // staff award or subtract up to five points
      if ($auth->acl_getf_global('m_') || $karmamod->user_level == 'admin')
      {
         $max_karma_power = $karmamod->config['power_max'];
      }
      else
      {
         $days_registered = (int) max(2, round(($karmamod->current_time - $user->data['user_regdate']) / 86400));

         $max_karma_power = round($user->data['user_karma_powered'] / log($days_registered));

         if ($max_karma_power > $karmamod->config['power_max'])
         {
            $max_karma_power = $karmamod->config['power_max'];
         }
         else if ($max_karma_power < 1)
         {
            $max_karma_power = 1;
         }
      }

...

      $karmamod->submit_karma($data);
...

function submit_karma($data)
{ 
...

// Update poster's karma
$sql = 'UPDATE ' . USERS_TABLE . '
SET user_karma = user_karma ' . (($data['action'] == 'decrease') ? '-' : '+')  . ' 1,
user_karma_powered = user_karma_powered ' . (($data['action'] == 'decrease') ? '- ' : '+ ') . $data['karma_power'] . '
WHERE user_id = ' . $data['user_id'];

...
}