code: def Planck_wavelength(l, T):
      '''The Planck function (flux density for blackbody radiation)
      in wavelength space
      l is wavelength in meters
      T is temperature in Kelvin
  
      Formula (3.3) from Raymond Pierrehumbert, "Principles of Planetary Climate"
      '''
      u = hPlanck*c_light/l/kBoltzmann/T
      return 2*kBoltzmann**5*T**5/hPlanck**4/c_light**3*u**5/(exp(u)-1f Planck_wavelength(l, T):
      '''The Planck function (flux density for blackbody radiation)
      in wavelength space
      l is wavelength in meters
      T is temperature in Kelvin
  
      Formula (3.3) from Raymond Pierrehumbert, "Principles of Planetary Climate"
      '''
      u = hPlanck*c_light/l/kBoltzmann/T
      return 2*kBoltzmann**5*T**5/hPlanck**4/c_light**3*u**5/(exp(u)-1)
docs: The Planck function (flux density for blackbody radiation)
      in wavelength space
      l is wavelength in meters
      T is temperature in Kelvin
  
      Formula (3.3) from Raymond Pierrehumbert, "Principles of Planetary Climate"