understanding onesource::substellar

[johannct]

Several remarks :

• name is bad : should be something like substract_stellar_component_in_IR
• bool substar should not be passed as an argument; the condition on it should be in photoz_lib
• I do not understand the comment only for lambda_rf>25000 when compared to the condition allFilters[k].lmean / (1 + consiz) < 25.
• when ab[k]-fluxMod<0, abIR[k] is set to sab[k]. Why? I thought that in LePHARE allowing below 0 fluctuations of fluxes was a thing. What is the statistical rationale behind setting abIR[k] to sab[k]?
• if I am not mistaken the last else condition means that sab[k] has to be negative, right? In which case busfir[k] and bscfir[k] should already be 0 no?

If I understand well, this code amounts to subtracting the predicted flux from interpolation of the best fit (interpolation in magnitude in the space of the templates, occurring in interp_lib). So what remains are IR emission lines and what else?
This is what gets fitted in fitIR so it means that the additional library for IR has templates for this component not coming from standard library. Can you write down what these are please, so that I can also put some explanation in the C API.