 Usage:  ln = leafnum(cs, node)  
 
 Input:

  cs                     list of vectors: data structure which represents a binary tree 
                         and is produced by cartsplit procedure, contains vectors 
                         cs.val, cs.vec, cs.mean, cs.ssr, cs.nelem. 
                         See cartsplit for the description of cs. 
                         
  node                   integer >= 1: gives the index of the root node of 
                         the subtree whose number of leaves will be calculated. 
                         If node=1, the number of leaves in the hole tree is 
                         calculated, if node=2, the number of leaves in the 
                         left subtree is calculated, if node=3, the number 
                         of leaves in the left subtree of the left subtree 
                         (if it exists) is calculated. See cartsplit for 
                         the explanation how the tree is represented as a 
                         vector. 
                         
 Output:

  ln                     integer >= 1: number of leaves in the specified 
                         subtree. 
                         
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(C) MD*TECH Method and Data Technologies, 17.8.2000
