subroutine fout(output_file,ierr)
c
c hidden check of parameter 'filter_out' : 
c if 
c if 'filter_out:no' (default) --> return
c if 'filter_out:yes'  write into 'output_file'_filt the 3 
c                      filterd time history and EXIT --> ierr = -99
c a.tento 6/03 v.1.0
c
        implicit none
        include 'main.h'
        include 'parameters.h'
        include 'times.h'
c
        character*200 output_file
        integer ierr
c
        character argout(20)*200, sep2*1, output_filt*200
        parameter (sep2 = ':')
        integer j1, nunit, jlen, nw, i, j
        real sfre
c
c
        ierr = 0        
        call split3(filter_out,argout,sep2,nw)
        if ( argout(1)  .eq.  'no' ) return
c
        output_filt = output_file 
        j1 = jlen(output_filt)
        output_filt(j1 + 1:j1 + 7) = '_SAF_fi'
        call glun(nunit,ierr)
        if (ierr .eq. 1) then
        write (*,*) ' ERROR: FOUT: can not find free unit number'
        ierr=1
        return
        endif
c
        open(unit=nunit,file=output_filt,status='unknown')
c
c write a SAF file, at this point we have lost information contained
c in the original header (file could be saf, gse, cs)
c
        sfre = 1.0 / sampling_rate
        write(nunit,400)
        write(nunit,420)
        write(nunit,430)
        write(nunit,440) sfre
        write(nunit,450) n_samples 
        write(nunit,460)
        write(nunit,470)
        write(nunit,480)
        write(nunit,490)
        write(nunit,500)
        write(nunit,510)
c
        do 1 i = 1, n_samples
        write(nunit,*)(datath(i,j),j=1,3)
1       continue
c
        close(nunit)
c
c
        ierr =  -99
        return
c
c
400     format('SESAME ASCII data format (saf) v. 1     ')
420     format('STA_CODE = FIL')
430     format('START_TIME = 2003 06 14 14 40 30.000')
440     format('SAMP_FREQ = ',g15.7)
450     format('NDAT = ',i10)
460     format('CH0_ID = ver')
470     format('CH1_ID = ho1')
480     format('CH2_ID = ho2')
490     format('UNITS =  filtered')
500     format('# GAIN = 1.0')
510     format('####----------------------------------------')
c
c
        end