Switch to single canonical reference for unit conversion factors

[ianmackenzie]

Currently the process for determining the exact conversion factors used in different modules has been a bit ad-hoc - mostly just scouring Wikipedia for what seemed like the most generally-accepted and up-to-date value. Especially as we add more modules, it would be ideal to have a more uniform/rigorous process. I think a good start would be a combination of:

• NIST Handbook 44, Appendix C
• UK Weights and Measures Act 1985
• DIN 1301/German Units Act (PDF link)

There will likely be some units (different types of horsepower?) that aren't defined in any of the above and will need special treatment, but I think those would cover the majority of cases. Hopefully they are consistent where they overlap! Thoughts? Suggestions for alternate sources?

[katjam]

I spotted NIST and UK weights and measures also. Hadn't seen German Units Act but that also looks good. Let's cast around a bit and see if we get confirmation/ other suggestions. It'll be easy to swap out the conversion factors once we make the decision. No harm putting further functions in place now with our best efforts.

[ianmackenzie]

Sounds good, and agreed - don't have to block anything on this.

[ianmackenzie]

Not nearly as official, but very comprehensive and at least has links/references to where various factors came from: https://frinklang.org/frinkdata/units.txt

[katjam]

That does indeed look comprehensive & the sources in principle make it reliable. I'd suggest if we use it we aim to verify (at point of writing) with at least one other (official) source.

[katjam]

https://frinklang.org/frinkdata/units.txt is actually quite a fun read!

[katjam]

Consider https://www.bipm.org/en/measurement-units/

We have decided to go with NIST for now - but might be worth cross ref with the SI - French definitions internationally recognised.

[ianmackenzie]

Does that include conversion factors for non-SI units though? I just see stuff about the SI units themselves...

[katjam]

No probably not, I think they only define SI. Someone just linked me to it today and said it was the internationally recognised standard for scientific use. I've not looked into it further - but thought it might be worth doing so breifly since we'd not mentioned here before.