List Commands Library for 50g

[Thomas Okken]

(10-01-2017 02:21 PM)John Keith Wrote:  

(10-01-2017 12:56 PM)pier4r Wrote:  or (way longer but pinpointing)
{list} DUP SIZE RAND * 1 + IP GET

{ list } DUP SIZE RAND * CEIL GET is shorter and faster.

It’s not equivalent, though. With CEIL it is possible to get 0, and there is a correspondingly slightly lower probability of getting the maximum value. 1 + IP is the way to go; correctness trumps speed.

UPDATE: I just checked the manual (the 48SX manual from the MoHPC documentation set) and it says that RAND returns values in the range 0 <= x <= 1.

If that is true, then neither of the above code sequences are correct, because 1 + IP could return SIZE + 1. Seems weird though, I don’t think I’ve ever seen a random number function with that kind of range, it’s usually 0 <= x < 1 or some range of integers. Is the 48SX (and other RPL calculators?) weird in this regard, or is it a typo in the manual?

UPDATE 2: The Programmer's Reference Manual says 0 <= x <= 1, and the Owner's Manual says 0 <= x < 1.