function bfld(z,r,brfld)
c----------------------------------------------------------------------
c
      include 'param_sz.h'
      include 'bfieldcom.h'
      include 'flagcom.h'
      include 'pfieldcom.h'
      include 'syscom.h'
      include 'ucom.h'
c 
c----- Champ Poisson
c
      if(poiflag .and. (z.ge.pzmin.and.z.le.pzmax))then
         l=(z-pzmin)/pdz
         k=r/pdr
         f1=(pdz*(l+1)-z+pzmin)/pdz
         f2=1.-f1
         f3=(pdr*(k+1)-r)/pdr
         f4=1.-f3
         if(k.ge.nrp)then
             brfld=0.
             bfld=0.
         return
         endif
         brfld=f1*(f3*rbfld(k,l)+f4*rbfld(k+1,l))+
     *         f2*(f3*rbfld(k,l+1)+f4*rbfld(k+1,l+1))
         bfld=f1*(f3*zbfld(k,l)+f4*zbfld(k+1,l))+
     *        f2*(f3*zbfld(k,l+1)+f4*zbfld(k+1,l+1))
         return
      endif
c
c----
c
      if(ifld.ne.0 .and. (z.ge.zmin.and.z.lt.zmax))then
      i=(z-zmin)/dzz +1
cbm 04/02/2010
      if(i.gt.nptcb) then
        write(nnout,*) ' bfld i gt ',nptcb
        stop
      endif
      f1=(dzz*i-z+zmin)/dzz
      f2=1.-f1
      rsq=r**2
      bf1=bf(i,1)*f1+bf(i+1,1)*f2
      bf2=bf(i,2)*f1+bf(i+1,2)*f2
      bf3=bf(i,3)*f1+bf(i+1,3)*f2
      bf4=bf(i,4)*f1+bf(i+1,4)*f2
      bf5=bf(i,5)*f1+bf(i+1,5)*f2
      bf6=bf(i,6)*f1+bf(i+1,6)*f2
      bfld=bf(i,0)*f1+bf(i+1,0)*f2-rsq*(bf2-rsq*bf4/16.+
     *                                  rsq**2*bf6/576.)/4.
      brfld=-r*(bf1-rsq*bf3/8.+rsq**2*bf5/192.)/2.
      else
      bfld=0
      brfld=0
      endif
      return
      end
c++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*