*-- Author : I.O. Skillicorn
      SUBROUTINE FTLFTW(XS,YS,WS,L,KEY,KK,AS,BS,ES,DAS,DBS,COVS)
C     MOD TO VECTORIZE                                                                                        
C     TO PERFORM A WEIGHTED STRAIGHT LINE FIT  Y=AX+B                                                         
C     CERN LIBRARY ROUTINE MOD TO INCLUDE FIT TO Y=AX                                                         
C     CALCULATE SUMS   WEIGHT =1./ERROR                                                                       
C                                                                                                             
C     FIT PARAMETERS                                                                                          
C     ADDED 24/3/88                                                                                           
C                                                                                                             
C                                                                                                             
C     INSUFFICIENT POINTS                                                                                     
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C new version imported from IOS fortran 6/6/91                                                                
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