subroutine gel_hv(output_file,smv,smn,sme,fre,buf,nf,n_win,
     #                  sv,sn,se,nfft,jmin,jmax,ierr)
c
c for each window
c       merging horizontal component +
c       compute H/V +
c       [optional] write single component file --> h/v + spectra
c
c  a.tento 05/03 v.1.0.
c
        implicit none
c
        include 'parameters.h'
c
        character*200 output_file
        real sv,sn,se, smv, smn, sme, buf, fre
        integer ierr, jmin, jmax, nf, n_win, nfft
        dimension  fre(nf), sv(nfft), sn(nfft), se(nfft), buf(nf),
     #          smv(nf,n_win),smn(nf,n_win),sme(nf,n_win)
c
c
        integer jlen, j1, j2, ifsw, nw, i, l, nunit
c        real
        character sep2*1, swin_outf*200
        parameter (sep2 = ':')
        character*200 argout(20)
c
c
c
        call split3(single_win_out,argout,sep2,nw)
        if( argout(1)  .eq.  'no' ) then
         ifsw = 0
        else
         ifsw = 1
         call glun(nunit,ierr)
          if (ierr .eq. 1) then
           write (*,*) ' ERROR: GEL_HV could not find free unit number'
           ierr=1
           return
          endif
         swin_outf = output_file
         j1 = jlen(swin_outf)
         j1 = j1 + 1
         j2 = j1 + 5
         swin_outf(j1:j2)='_win_'
        endif
c
        do 1 l = 1, n_win
        if ( ifsw .eq.  1 ) then
                do 20 i = jmin, jmax
                        sv(i) = smv(i,l)
                        sn(i) = smn(i,l)
                        se(i) = sme(i,l)
20              continue
        endif
c
        call merge_hv(l,smv,smn,sme,nf,n_win,buf,jmin,jmax,ierr)
        call ckerr(ierr)
c
        if ( ifsw .eq.  1 ) then
               call swin_write(nunit,swin_outf,l,fre,smv,smn,sme,nf,
     #  n_win,sv,sn,se, nfft,jmin,jmax,ierr)
               call ckerr(ierr)
        endif
c
1       continue
c
c
        return
c
        end