Compute the probability of escape for photons emitted uniformly in a homogenous sphere of absorbers, possibly with scattering. Compute effective optical depth of a sphere including scattering. Effective optical depth is estimated by interpolating a grid of Monte Carlo simulations stored in a structure in common. Inputs can be scalar or arrays, but must be all same dimensions. The user can modify the model control parameters with X-widget GUI that is automatically presented, or just accept the default values.
Data can be an observed image or spectrum, result is always positive.
Maximum Likelihood formulation can assume Poisson noise statistics or Gaussian additive noise, yielding two types of iteration. An approximation for the ionization of Hydrogen, and resultant heating of dust by Lyman-alpha photons is also attempted. In otherwords, it gives the interacting fraction of a collection of randomly impacting photons. If the scattering albedo is given, then the actual absorbed fraction is computed approximately. When scattering is specified to be purely forward then an exact formula used.