 Usage:  y = cartregr (tree, x {, stri})  
 
 Input:

  tree                   list, result of cartsplit 
                         
  x                      nxp, X-variables 
                         
  stri                   text, which values should be returned 
                         
 Output:

  y                      nx1, result 
                         
--------------------------------------------------------------
(C) MD*TECH Method and Data Technologies, 17.8.2000
