anchor.diff:      
   end subroutine sigmay_func
       
  +    
   ! calculates the vertical spread of the wake at a given distance from the onset of far 
   ! wake condition
   subroutine sigmaz_func(kz, deltax0, rotor_diameter, sigmaz)
  
positive.code: 
  end subroutine porteagel_visualize
  
  ! calculates the onset of far-wake conditions
  subroutine x0_func(rotor_diameter, yaw, Ct, alpha, I, beta, x0)
  
  
negative.code: 
              ! near wake region (linearized)
              else if (deltax0 > -x0) then
      
                  ! horizontal spread
                  call sigmay_func(ky, deltax0, rotorDiameter(turb), yaw(turb), sigmay)
                  
  