Subroutine ffhe3 (q2mev,rp,rn,rpsp,rnsp,nfcn,ache,amhe,ach)
c *** see RH Landau, Program lpott, 1981, mods by m sagen
c     m paez eliminated use of fmmm- McMillan 3-nucleon ff
c     ffhe3 calculates the four form factors needed to describe he3with
c     (fsd is only calc as a cpmparison, it should be small and is
c     the apptox, or effectove, sd contib to the magnetic ff
c     the ff*s are calc by using
c       1 fche3- expt of 7ccarthy et al for all q2,have fitted
c       2 ff*s calc by m McMillan,for fcn=0 these fit h3 data
c         of collard and for larger q2( gt 6 f-2) they rep a
c         reasonable extrapltn which has a correct zero as he3
c     3 fmhe3 use the form of 7ccarthy et al but vary this since the exh
c     chage contib is included in e scatter, but presmbly not in our pi
c     scatt (nb we use mu he3 = un)
c     these ff include s,s* + d states exactly in f1c,f2c,
c     the d state is only put in approximatly in f1m,f2m as Gibson has
c     shown this to be small (ignore too the dd terms too)
c     nfcn=1 , include neutron form factor in escat data, =0 , Don*t
c     data seems best interpreted with no neutron ?charge? form factor
c     possibly this is due to polarization or meson exch efects &&
c
c     q2mev2 is in mev**2 not Fermi-2
      Implicit Real*8(a-h,o-z)
      data up,un,uhe3/2.79278,-1.91315,-1.91315/
      q2f2 = q2mev/(197.329**2)
      qf = Sqrt(q2f2)
c     nucleon ff
      fn=0.
      fp=1.
      If(nfcn.eq.0) Call ffpn (q2f2,fp,fn)
      If ((nfcn.ne.1).and.(nfcn.ne.0)) Write (6,40) nfcn
c     he3 and h3 charge ff
      fche3 = ffche3(qf)
c     use mmm wf*s for h3,this fits collard (if fn=0) and is reasnb,e
c     sp= s* prob, pd= d state prob, these a can be varied
      psp = 0.02
      pd = 0.09
c      Call fmmm (q2f2,f1c,f2c,psp,pd)
c      fch3 = (2.*fn+fp)*f1c+(fp-fn)*f2c
c     he3 mag ff
      fmhe3 = ffmhe3(qf)
      GoTo 30
      entry fhe3gs(q2mev,rp,rn,rpsp,rnsp,nfcn,ache,amhe,ach)
      q2f2 = q2mev/(197.32**2)
      fn = 0.
      fp = 1.
c     Gaussian form factors
      fche3 = 0.
      rhl = ache*ache*q2f2
      If (rhl.gt.150.) GoTo 10
      fche3 = exp(-rhl)
 10   fch3 = 0.
      rhl = ach*ach*q2f2
      If (rhl.ge.150.) GoTo 20
      fch3 = exp(-rhl)
 20   fmhe3 = 0.
      rhl = amhe*amhe*q2f2
      If (rhl.ge.150.) GoTo 30
      fmhe3 = exp(-rhl)
 30   Continue
c
c     direct calc of ff for fcn=0
      rp=fche3/fp
      rn=fch3/fp
      rhl=un/(up+2.*un)/fp
      rhl1=(fch3-4.*fche3)/3.
      rpsp=rhl*(fmhe3+rhl1)/2.
      rnsp=rhl*(2.*fmhe3-rhl1*(up/un))
      Return
c
 40   format (55h ********** neutron form factor switch is strange,nfcn=
     1,i3,11h **********,/)
      End