def METHOD_NAME(v,th,y0=0,g=9.8):
  """
    Calculates the analytic time of flight
    @ In, v, float, velocity of the projectile
    @ In, th, float, angle to the ground for initial projectile motion
    @ In, y0, float, optional, initial height of projectile
    @ In, g, float, optional, gravitational constant (m/s/s)
    @ Out, time_to_ground, float, time projectile is above the ground
  """
  return v*np.sin(th)/g + np.sqrt(v*v*np.sin(th)**2+2.*g*y0)/g