anchor.diff:        inv_n = 1.0d0/n
         agr2  = agr*agr
   
  -      p       =  agr2/(4.0d0*P23*n_83)
  -      p_14    =  dsqrt(dsqrt(1.0d0/(4.0d0*P23)))*dsqrt(agr)/n_23 
  +      ex0  = Cx*n_13
  +      nex0 = n*ex0
  +
  +      p       =  agr2/(4.0d0*P23*n_83)                             !*** p = s**2       ***
  +      p_14    =  dsqrt(dsqrt(1.0d0/(4.0d0*P23)))*dsqrt(agr)/n_23   !*** p_14 = sqrt(s) ***
         dp_dn   = -etthrd*p*inv_n
         dp_dagr =  2.0d0*p/agr
   c     dp_dtau =  0.0d0
  
positive.code:       real*8 exp1,exp2,exp3,exp4,exp5
        real*8 x1,x2,x,dx1_dp,dx2_dp,dx_dp,dx_dalpha
        real*8 denh1x,numh1x,h1x,dh1x_dx,dh1x_dp,dh1x_dalpha
        real*8 gx,dgx_dp
        real*8 fxa,dfxa_dalpha
        real*8 Fx,dFx_dp,dFx_dalpha,dFx_dn,dFx_dagr,dFx_dtau
        real*8 ex0,nex0
  
negative.code:         fdtauc = n*dfca_dtau*(ec0 - ec1)
  
          
  
          xce(i)   = x_parameter*ex     + c_parameter*ec
          fn(i)    = x_parameter*fnx    + c_parameter*fnc
          fdn(i)   = x_parameter*fdnx   + c_parameter*fdnc
  