Science Model Pack Parameter Specification

[karllark]

How to set the parameters in the models
How to interface this to real humans.

[karllark]

astropy.modeling has a standard on how to specify the parameters, values, and bounds. And ties.
@jdtsmith : does that address the first point?

[jdtsmith]

I'm more interested in how the science-savvy end user could alter a given science model pack or modify one of the base packs. What flexibility do we need? At minimum:

• Full and expandable parameter set for all emission, absorption, and continuum features
• Easy to specify for the end user (e.g.: add a new named emission line, in one line)
• Expressive, so you can readily express constraints (>x and/or <y), and even ties between parameters, e.g. strength(feature1)= [0.8,1.2] * strength(feature2)

This relegates most PAHFIT hacking to working with the science model packs. Obviously these need to be well documented.

[jdtsmith]

@els1 This is where we started discussing the science pack (looks like I had an issue already after all). Features we want:

starlight: ..... 
continuum: ....
dust_features: ....
line_features: ...
attenuation: ...

Now all we have to do is fill in in the ...'s. And identify any "extras".

Goal: expressive enough to accommodate whatever model flexibility we want in the future, but not so cumbersome as to be useless. A sub-feature of all these ...'s is how to generically express constraints in such a human readable model. I've started a new issue to discuss constraint notation in #33.

Here's lets just discuss the science model flexibility we want to enable by default, that should cover the basic use cases of Galactic & Extragalactic PAH-emitting sources, even when sensitivity and resolution jump by 10-50x.

[karllark]

A start on this is given in PR #44 (table format) and PR #45 (YML format). The table format needs to be integrated in and the YML format needs a reader and the same. I'm going to make separate issues for this and refer back to this issue.