subroutine lyahhe(xl,ahe,prof)
c     ==============================
c
c     Lyman alpha broadening by helium - after N. Allard
c
      INCLUDE 'PARAMS.FOR'
      parameter (nxmax=1000)
c     parameter (sthe=1.e21)
      common/hhebrd/sthe,nunhhe
      common/calhhe/xlhhe(nxmax),sighhe(nxmax),nxhhe
      dimension xlhh0(nxmax),sighh0(nxmax)
      data iread/0/
c
      if(iread.eq.0) then
c        nxhhe=679
c        open(unit=67,
c    *   file='siglyhhe_21_T14500.lam',
c    *   status='old')
         it=0
         do i=1,nxmax
            read(67,*,err=5,end=5) xl,sig
            it=it+1
            if(nunhhe.eq.1) xl=1./(1.e-8*xl+1./1215.67)
            xlhh0(it)=xl
            sighh0(it)=sig
         end do
    5    nxhhe=it
         do i=1,nxhhe
            xlhhe(i)=xlhh0(nxhhe-i+1)
            sighhe(i)=sighh0(nxhhe-i+1)
         end do
c        do i=1,nxhhe
c           j=nxhhe-i+1
c           read(67,*) xlhhe(j),sighhe(j)
c        end do
         close(67)
         iread=1
      end if
c
      prof=0.
      if(xl.gt.xlhhe(nxhhe)) return
      jl=0
      ju=nxhhe+1
 10   if(ju-jl.gt.1) then
         jm=(ju+jl)/2
         if((xlhhe(nxhhe).gt.xlhhe(1)).eqv.(xl.gt.xlhhe(jm))) then
            jl=jm
         else
            ju=jm
         endif
         go to 10
      endif
      j=jl
c
      if(j.eq.0) j=1
      if(j.eq.nxhhe) j=j-1
      a1=(xl-xlhhe(j))/(xlhhe(j+1)-xlhhe(j))
      s1=(1.0-a1)*sighhe(j)+a1*sighhe(j+1)
      prof=s1*ahe/sthe*6.2831855
      return
      end