anchor.diff:  ! __   __  _ __  ___  ___ _   _  __| | ___  
   ! \ \ / / | '_ \/ __|/ _ \ | | |/ _` |/ _ \ 
   !  \ V /  | |_) \__ \  __/ |_| | (_| | (_) |
  -!   \_/   | .__/|___/\___|\__,_|\__,_|\___/ 
  +!   \_/   | .__/|___/\___|\__,_|\____|\___/ 
   !         | |                               
   !         |_|                               
   
  
positive.code:         do k=1,kmax
            do l=0,lmax
            array_R(ktot,k,l,lambda,lambdap)= freal & 
                                              *int_prod_bessel(ktot+2,g_a+g_b+dz_kl(k,l),lambda,lambdap,areal,breal)
            enddo
          enddo
     enddo
  
negative.code:       do l=0,lmax
  
          array_R(ktot,k,l,0,lambdap)= freal & 
                                       * int_prod_bessel_num_soph_p(ktot+2,g_a+g_b+dz_kl(k,l),0,lambdap,areal,breal,arg)
         enddo
      enddo
    enddo
   enddo
  