Oracle : Index Fragmentation

This script provides information critical in determining whether an  index is a candidate for rebuilding.  An index is a candidate for 
rebuilding when a relatively high number of index leaf row deletes have  occured.  

set verify off  
def ownr  = &&1  
def name  = &&2  
  
ttitle - center 'Index Fragmentation Statistic'   skip 2 
  
set heading off  
  
col name                 newline  
col lf_blk_rows          newline  
col del_lf_rows          newline  
col ibadness newline   
  
validate index &ownr..&name;  
  
select  
  'index name        '||name,  
  'leaf rows deleted '||to_char(del_lf_rows,'999,999,990')  del_lf_rows,  
  'leaf rows in use  '||to_char(lf_rows-del_lf_rows,'999,999,990')  lf_blk_rows,  
  'index badness     '||to_char(del_lf_rows/(lf_rows+0.00001),'999,990.999') ibadness  
from  
  index_stats  
/  
  
undef ownr  
undef name  
set verify on