 Usage:  line = grcart2(x,tree,ix,iy,mindepth,minssr)  
 
 Input:

  x                      nxp, X-variables used in cartsplit 
                         
  tree                   list, result of cartsplit 
                         
  ix                     scalar, which variable is taken for X 
                         
  iy                     scalar, which variable is taken for Y 
                         
  mindepth               scalar, till which depth the tree should be shown 
                         
  minssr                 scalar, shows all cuts which produce a SSR larger than minssr 
                         
 Output:

  line                   list, a graphical object that contains the cuts 
                         
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(C) MD*TECH Method and Data Technologies, 17.8.2000
