More efficient PERK implementation

[DanielDoehring]

Essentially this bundles some functions and reduces the number of assignments at the expense of repeated arithmetic operations.

@warisa-r can you take a first look?

[github-actions]

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[codecov]

Codecov Report

Attention: Patch coverage is 94.64286% with 3 lines in your changes missing coverage. Please review.

Project coverage is 96.39%. Comparing base (824f7a8) to head (51a2103).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...xplicit_runge_kutta/paired_explicit_runge_kutta.jl	76.92%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2180      +/-   ##
==========================================
+ Coverage   96.37%   96.39%   +0.02%     
==========================================
  Files         483      483              
  Lines       38333    38320      -13     
==========================================
- Hits        36943    36938       -5     
+ Misses       1390     1382       -8     

Flag	Coverage Δ
unittests	96.39% <94.64%> (+0.02%)	⬆️

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[warisa-r]

The new functions look more compact and are valid for s = e, the only relevant case for single methods as you mentioned before. However, should we also document that standalone methods only handle s = e? #2146

[DanielDoehring]

The new functions look more compact and are valid for s = e, the only relevant case for single methods as you mentioned before. However, should we also document that standalone methods only handle s = e? #2146

Yes, if this not mentioned yet explicitly we should do that 👍

[warisa-r]

The new functions look more compact and are valid for s = e, the only relevant case for single methods as you mentioned before. However, should we also document that standalone methods only handle s = e? #2146

Yes, if this not mentioned yet explicitly we should do that 👍

Done!

[JoshuaLampert]

I just have a few small questions.

[JoshuaLampert]

Thanks!

[torrilhon]

Please note #1880 ...