anchor.diff:  
   end subroutine porteagel_visualize
   
  +! calculates the onset of far-wake conditions
   subroutine x0_func(rotor_diameter, yaw, Ct, alpha, I, beta, x0)
   
       implicit none
  
positive.code:         call x0_func(rotorDiameter(turb), yaw(turb), Ct(turb), alpha, I, beta, x0)
          
          ! determine the initial wake angle at the onset of far wake
          theta_c_0 = 0.3_dp * yaw(turb) * (1.0_dp - sqrt(1.0_dp - Ct(turb) * cos(yaw(turb)))) / cos(yaw(turb))
  
          do, turbI=1, nTurbines ! at turbineX-locations
          
              ! downstream distance between turbines
  
negative.code:     )
  end subroutine wake_offset_func
  
  ! calculates the velocity difference between hub velocity and free stream for a given wake
  subroutine deltav_func(deltay, deltaz, wake_offset, wind_speed, Ct, yaw, sigmay, sigmaz, &
                         & rotor_diameter, deltav) 
                         
  