 Usage:   data=getdata(di, row_num, col_num, data_num)  
 
 Input:

  di                     Display 
                         
  row_num                integer, 1, ..., count of lines of di 
                         
  col_num                integer, 1, ..., count of columns of di 
                         
  data_num               integer, 1, ..., count of data sets plotted in this plot 
                         
 Output:

  data                   a complex object that includes following components: 
                         
                         a matrix of the points 
                         
  pcolor                 a (nx3) matrix of color 
                         
  pstyle                 (nx1), style 
                         
  psize                  (nx1), size. 
                         
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(C) MD*TECH Method and Data Technologies, 17.8.2000
