[SiempreViernes]

I don't know man, the link you clicked on says "Derive Yourself a Kalman Filter", so complaining about a formal treatment seems misguided rather than simply unfair.

[your-nanny]

you are assuming that the reader is familiar with this specific understanding of "derive". someone not familiar with formal methods wouldn't.

[mlevental]

what other understanding of derive is there???

[coolgeek]

Derived data - e.g. indexes or summaries.

Derivative financial instruments - e.g. options, CDSs.

I'm sure there are many more examples.