program inflation_factor
!**********************************************************************
! *              .      .    .
! * PROGRAM:    INFLATION_FACTOR
! * PRGMMR:     D. ZUPANSKI     ORG: CIRA/CSU   DATE: 2004-07-02
! *
! * ABSTRACT:   CALCULATE INFLATION FACTOR ALPHA TO SATISFY CHI-SQUARE TEST
! *
! * PROGRAM LOG:
! *
! * 10/21/2003    ..... M. ZUPANSKI:
! *
! **********************************************************************
!----------------------------------
!  INPUT: 
!         x_innov       - Innovations
!
!  OUTPUT:
!         alpha=sqrt((2.*J_obs-N_obs)/traceA)
!
!----------------------------------
!-----
     integer,parameter::icost=20         ! input file #
     integer,parameter::ifile1=21         ! input file #
     integer,parameter::ifile2=22         ! input file #
     integer,parameter::infl_factor=51    ! output file #
!-----
     integer :: N_obs

     real :: alpha,obsinf_cont
     real,dimension(:),allocatable:: x_innov
     real :: COST_obs,COST_pen,COST_b,COST_total
!-----
!==============start calculation===================

!-- read control residuals (innovations)
     rewind ifile1
     read(ifile1) N_obs
     allocate(x_innov(1:N_obs))
     read(ifile1) x_innov

     write(*,*) "N_obs=",N_obs

      CLOSE(icost)
      OPEN(UNIT=icost,FILE='outcostc',FORM='FORMATTED',IOSTAT=IER)
      READ(icost,200) ii,COST_obs,COST_pen,COST_b,COST_total
      CLOSE(icost,STATUS='KEEP')
 200  FORMAT(I5,4E20.10)

!-- read traceA---------------
     rewind ifile2
     read(ifile2,*) obsinf_cont

!----alpha--------------------
     alpha=sqrt((2.*COST_total/N_obs)/obsinf_cont)
     alpha=10.*alpha

      rewind infl_factor
      write(infl_factor,*) alpha

     write(*,*) " Inflation factor alpha=",alpha

            end program inflation_factor