(feat) improve rss_errors() using a functional programming approach

[ThibFrgsGmz]

• Improve docstrings on rss_* utility functions from utils.rs
• Make rss_errors kind of more idiomatic using a functional programming way

I tried to put some UT but I did not well understood how to do them.

For example, we could have:

    #[test]
    fn test_rss_errors() {
        let prop_err = OVector::from_vec(vec![1.0, 2.0, 3.0]);
        let cur_state = OVector::from_vec(vec![1.0, 2.0, 3.0]);
        assert_eq!(rss_errors(&prop_err, &cur_state), 0.0);

        let prop_err = OVector::from_vec(vec![1.0, 2.0, 3.0]);
        let cur_state = OVector::from_vec(vec![4.0, 5.0, 6.0]);
        assert_eq!(rss_errors(&prop_err, &cur_state), 5.196152422706632);
    }

But I currently have some compiler complains about from_vec, so I gave up and trust the CI.

I hope to get feedback from you on this subject!

[codecov]

Codecov Report

Patch coverage: 70.83% and project coverage change: +0.15 🎉

Comparison is base (2ee5225) 66.33% compared to head (e107020) 66.49%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #177      +/-   ##
==========================================
+ Coverage   66.33%   66.49%   +0.15%     
==========================================
  Files         127      127              
  Lines       32445    32455      +10     
==========================================
+ Hits        21524    21580      +56     
+ Misses      10921    10875      -46     

Impacted Files	Coverage Δ
src/utils.rs	58.95% <70.83%> (+7.55%)	⬆️

... and 4 files with indirect coverage changes

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[ChristopherRabotin]

We can add some unit tests for sure. At the moment, these two functions are used in the propagator when we're using an adaptive time step, so they're frequently hit. The results of the propagators exactly match GMAT, so I'm pretty confident that they're correct and that any new bug in those functions would be caught immediately.

If you want to add units tests, I wrote a quick example of different common ways to initialize a vector using nalgebra: https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=00f15985f45e6c43e3ab1469bd310cb3 .

[ChristopherRabotin]

Good idea! I initially seem to have written this in April 2018 (the 2021 commit is got a change in nalgebra), and that was before I used any FP in Rust.

[ThibFrgsGmz]

I added the UT based on the way you created OVector in the code snippet you shared.

[ChristopherRabotin]

Suggested change

	/// * A f64 value representing the RSS state error.
	/// A f64 value representing the RSS state error.

(minor) I don't think we need this to be a bullet point

[ThibFrgsGmz]

Done.

[ChristopherRabotin]

Suggested change

	/// * A tuple of f64 values representing the RSS orbit errors in radius and velocity.
	/// A tuple of f64 values representing the RSS orbit errors in radius and velocity.

(minor) idem

[ThibFrgsGmz]

Done.

[ChristopherRabotin]

Suggested change

	/// * A tuple of f64 values representing the RSS orbit vector errors in radius and velocity.
	/// A tuple of f64 values representing the RSS orbit vector errors in radius and velocity.

[ThibFrgsGmz]

Done.