GET_NODE_SCAT - returns the PDDP node with the maximum scatter 
  value (see PDDP)
    [MAX_SCAT_IND, M_SCAT]=GET_NODE_SCAT(TREE_STRUCT, SPLITTED) 
    returns the node index and the scatter value of the PDDP 
    tree defined by TREE_STRUCT. SPLITTED is a vector that 
    determines the active nodes. 
 
  Copyright 2011 Dimitrios Zeimpekis, Eugenia Maria Kontopoulou, 
                 Efstratios Gallopoulos