PHP error with Computed field here is my code:  

$nid = $entity-&gt;field_empf_number['und']['0']['nid'];  
$result = db_query("SELECT MAX(entity_id) FROM field_data_field_empf_number WHERE field_empf_number_nid = $nid")-&gt;fetchField();  
if (isset($result)){  
  $n = $result ;  
  $node = node_load($n);  
  $node-&gt;field_empf_stat['und']['0']['value'] = 'off';  //list field  
  node_save($node);  
}  
$entity_field[0]['value'] = $result;`


when add new node (if there is previous node i mean the if statement return true ) this error message show up:  


  Fatal error: Maximum function nesting level of '100' reached,
  aborting! in C:\wamp\www\finance\includes\database\database.inc on
  line 429


I googled but i did not found any answers.
Try to change the node_save($node) to drupal_register_shutdown_function('node_save', $node). It will remove the old node saving process from the actual node saving. 
But I don't think, that type of code should have place within a computed field. The computed field good to modify the same field. It isn't designed for modifying other data of your system.
These code should be in a custom module in hook_node_presave().