anchor.diff:      ! Mod from SixTrack
       ! ---------------------------------------------------------------------------------------------- !
       use numerical_constants, only : zero, one
  -    use mathlib_bouncer,     only : log10_mb
       
       implicit none
       
  
positive.code: 
  
        !                 ** Change of variable
        !call Horner2D_Ax(x, y, i, n, m, s, lx, ij_Ax, TAx, valA)
        call this%Horner2D_Ax(x, y, i, valA)
        px=px+valA
        !call HornerDYIntX_Ax(x, y, i, n, m, s, lx, ij_Ax, TAx, valA)
        call this%HornerDYIntX_Ax(x, y, i, valA)
        py=py+valA
  
  
        !             * h2
        !call HornerDX_Az(x, y, i, n, m, s, lz, ij_Az, TAz, valA)
        call this%HornerDX_Az(x, y, i, valA)
        px=px+dzover2*valA
        !call HornerDY_Az(x, y, i, n, m, s, lz, ij_Az, TAz, valA)
        call this%HornerDY_Az(x, y, i, valA)
        py=py+dzover2*valA
  
  
negative.code:     ! Mod from SixTrack
      ! ---------------------------------------------------------------------------------------------- !
      use numerical_constants, only : zero, one
      
      implicit none
      
  