code: def angledependentairtransmission(twotheta, mu_air, sampletodetectordistance):
      
      return np.exp(mu_air * sampletodetectordistance / np.cos(twotheta))
docs: Correction for the angle dependent absorption of air in the scattered
      beam path.
  
      Inputs:
              twotheta: matrix of two-theta values
              mu_air: the linear absorption coefficient of air
              sampletodetectordistance: sample-to-detector distance
  
      1/mu_air and sampletodetectordistance should have the same dimension
  
      The scattering intensity matrix should be multiplied by the resulting
      correction matrix.