How to return array of doubles?

[JLBorges]

> The reasons given for it are just arm waving to support a preference
> by the folks that came up with it and followers.

AFAIK, it is only by Sutter and diehard Sutter fans.

For instance, CoreGuidelines is far more sensible:

Use auto to avoid redundant repetition of type names

Example: ...
In each case, we save writing a longish, hard-to-remember type that the compiler already knows but a programmer could get wrong.

Avoid auto
. for initializer lists
. in cases where you know exactly which type you want
. where an initializer might require conversion.
https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Res-auto