text: # -*- coding: utf-8 -*-
  
  from numpy import pi, sin, arcsin
  
  
  def comp_surface_wind(self):
      """Compute the Slot inner surface for winding (by analytical computation)
  
      Parameters
      ----------
      self : SlotW24
          A SlotW24 object
  
      Returns
      -------
      Swind: float
          Slot inner surface for winding [m**2]
  
      """
  
      Rbo = self.get_Rbo()
  
      if self.is_outwards():
          Rint = Rbo
          Rext = Rbo + self.H2
      else:
          Rint = Rbo - self.H2
          Rext = Rbo
  
      # Surface of a slot pitch
      Sring = (pi * Rext ** 2 - pi * Rint ** 2) * 1 / self.Zs
  
      # Tooth surface
      St = self.H2 * self.W3
  
      alpha_bore = 2 * arcsin(self.W3 / (2 * Rint))
      Sarc_bore = (Rint ** 2.0) / 2.0 * (alpha_bore - sin(alpha_bore))
  
      alpha_yoke = 2 * arcsin(self.W3 / (2 * Rext))
      Sarc_yoke = (Rext ** 2.0) / 2.0 * (alpha_yoke - sin(alpha_yoke))
  
      if self.is_outwards():
          return Sring - (St + Sarc_yoke - Sarc_bore)
      else:
          return Sring - (St - Sarc_yoke + Sarc_bore)
  