def METHOD_NAME(wavelength):
  """Use Pappus's centroid theorem.  Direct quote from Wikipedia:  The volume of a solid
     of revolution generated by rotating a plane Figure F about an external axis is equal to
     the product of the area of F and the distance traveled by its geometric centroid.
     Thus for the Ewald sphere the Figure F has [area = pi * K^2], and the centroid travels
     [distance = 2 * pi * K] therefore [volume = 2 * pi^2 * K^3]"""
  return 2. * math.pi * math.pi / math.pow(wavelength,3)