General question about Stan function reference manual


Recently when I checked the Stan function reference manual, I am confused about the following about this simple sqaure root function:

What does the ‘R’ and ‘T’ mean here?

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I think it means that this function is vectorized*, not 100% sure though. So it takes any of the numerical types (int, reals, vectors, …). For example on the same page pow is not vectorized (you actually need to use it in a loop if you want to apply it to a vector/array).

That’s at least how I understand it.


*) Doesn’t necessarily mean that it’s faster than looping. It’s not that kind of vectorization.