add h3 misc functions - part 1

[bharatnc]

Changelog category (leave one):

• New Feature

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

Add new h3 miscellaneous functions: h3DegsToRads, h3RadsToDegs, h3HexAreaKm2, h3CellAreaM2, h3CellAreaRads2.

Detailed description / Documentation draft:

Add new h3 miscellaneous functions: h3DegsToRads, h3RadsToDegs, h3HexAreaKm2, h3CellAreaM2, h3CellAreaRads2 as per: https://h3geo.org/docs/api/misc/

Splitting up adding the functions into smaller PRs so that it's easy to review - will add the remaining misc functions separate PRs.

Related to #17708.

[kitaisreal]

Consider to cast argument column to function return type, to avoid virtual calls.

[alexey-milovidov]

@bharatnc

What's the purpose of adding h3DegsToRads and h3RadsToDegs?
It looks like it is some special way to convert between degrees to radians.
But there should not be any special ways to do it.

Let's either remove these functions
or introduce new functions DEGREES and RADIANS for SQL compatibility.

[bharatnc]

@bharatnc

What's the purpose of adding h3DegsToRads and h3RadsToDegs? It looks like it is some special way to convert between degrees to radians. But there should not be any special ways to do it.

Let's either remove these functions (preferred) or intdoduce new functions DEGREES and RADIANS for SQL compatibility.

@alexey-milovidov h3DegsToRads and h3RadsToDegs use the conversion functions exposed by h3 which as far as I can tell don't do anything special but just do the standard conversion from rads to degrees and vice versa. I added it purely for api completeness with what's found in https://h3geo.org/docs/api/misc/. Though I should admit that I did think about adding a generic functions to convert from Degrees to Rads and vice versa for general SQL needs.

I guess I am fine to do either one of these:

• Remove h3DegsToRads and h3RadsToDegs.
• Add DEGREES and RADIANS instead.

Probably adding DEGREES and RADIANS could be a better way ?

If we end up removing h3DegsToRads and h3RadsToDegs we can optionally add note in h3 docs to use DEGREES and RADIANS functions in place for h3DegsToRads and h3RadsToDegs as they don't do anything extra special.

[alexey-milovidov]

Probably adding DEGREES and RADIANS could be a better way?

Yes, let's do it!

[bharatnc]

Probably adding DEGREES and RADIANS could be a better way?

Yes, let's do it!

Great, I will work on adding those funcs next.