Plot unfolded data and model

[phajy]

This is a draft PR for plotting unfolded data and model (see #82). This draft will use the XSPEC method of calculation. It is a WIP and not ready to be merged. There are a couple of things I don't know how to do, and perhaps a bug I need to chase down.

[phajy]

This now produces unfolded E F_E plots that match those in XSPEC (produced using XSPEC's plot eeufs command). The key change that was required in the last commit was to divide by $\Delta x$ to get the fluxes in "per keV" units.

• The code needs to be tidied up.
• It would be awesome for units to propagate through everything then the axes could be automatically labelled.
• There are some data.data.'s that ultimately need cleaning up.
• The "power" should be a parameter (I think it is now) so it is easy to plot unfolded, F_E, and E F_E plots where we multiple by 1, E, and E squared, respectively.
• Allow the legend to be turned on/off.
• Remove the diagnostic print statements.
• Do we want the model to be stepped like in XSPEC?

Here are two example plots. The first from XSPEC the second from SpectralFitting showing good agreement.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 45 lines in your changes missing coverage. Please review.

Project coverage is 63.22%. Comparing base (6ab9ac7) to head (7a19436).
Report is 21 commits behind head on main.

Files	Patch %	Lines
src/plots-recipes.jl	0.00%	45 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #111      +/-   ##
==========================================
- Coverage   66.24%   63.22%   -3.03%     
==========================================
  Files          41       41              
  Lines        2216     2344     +128     
==========================================
+ Hits         1468     1482      +14     
- Misses        748      862     +114     

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[fjebaker]

@phajy I've added two commits and marked ready for review, if that's okay?

[fjebaker]

See also #113

[phajy]

Thanks @fjebaker. This looks great and I am happy for you to merge is with the main branch.