      function ffche3 (q)
      implicit real*8(a-h,o-z)
c *** see r h landau, program lpott, 1981
c     charge form factor for he3 from mccarthy et al, prl25,884,1970
c     q in f- 1
c           /60.1,70.4,3-e59.5-,24357.,88251.,984664./p,0q,d,2c,2b,2a at
c          /147.,98.3,3-e16.7-,014646.,82611.,988444./p,0q,d,2c,2b,2a at
c
      common/sec4/a2m,b2m,c2m,a2,b2,c2
      data d,q0,p/ -6.78e-3,3.98,0.90/
cccc  data a2,b2,c2,d,q0,p/.455625,.13396,.698896, -6.78e-3,3.98,0.90/
      q2 = q*q
      rhl1 = 0.
      if(q2.gt.24.)goto 40
      rhl = a2*q2
      if (rhl.ge.150.) go to 10
      rhl1 = exp(-rhl)
 10   rhl2 = 0.
      rhl = c2*q2
      if (rhl.ge.150.) go to 20
      rhl2 = -b2*q2*exp(-rhl)
 20   rhl = ((q-q0)/p)**2
      rhl3 = 0.
      if (rhl.ge.150.) go to 30
      rhl3 = d*exp(-rhl)
 30   ffche3 = rhl1+rhl2+rhl3
      return
c     arnold et al fch(he30 for largest q
 40   ffche3=0.
      rhl=0.1059*q2
      if(rhl.ge.150.)return
      tau=q2/4./202.5
      rhl1=sqrt((1.+tau)/(1.+4.527*tau))
      ffche3=rhl1*0.034*exp(-rhl)
      return
c**  this program valid on ftn4 and ftn5 **
      end
