[34S] Proposal for Entry RPN mode with dynamic stack

[matthiaspaul]

(02-16-2015 05:18 PM)Bit Wrote:  The behavior of ENTER is another thing that could break programs. Programs would need to be able to save, change and restore that setting, too.

Yes. So, depending on if this would be coupled to the same flag as the dynamic stack, we'd need one or two UState flags.

I'd prefer the two flags version, but we should be conservative in allocating flags, as we might need a few more flags for other features in the future. In some cases, "unfolding" state information into separate flags (like Nigel's and your's significant numbers feature) might help to decrease the size of the code necessary to evaluate such flags. I don't propose to change this now, but we might need to keep that in mind as an area for possible future optimization.

Quote:By the way, what would be the advantage of this on a calculator like the 34S? Is it simply that some people are used to it and why not make it easier for them (not a bad goal IMO), or do you think it's a superior UI? If it's the latter, then could you please explain why?

I guess, it is a mix of all of this. :-) Making it more easy and reliably to use (without retraining) to a wider audience is certainly one of the goals. Desired flexibility not only as a sign of excellence in a product, but also to have more people stress-testing the implementation and possibly contributing to this and follow-up projects.
Both methods have advantages and disadvantages, therefore it is difficult to declare one as better as the other. Classical RPN is slightly more keystroke efficient and powerful in a 4-level stack model, but it needs to be explained and mastered, whereas Entry RPN is slightly more intuitive and straight-forward and therefore easier to learn for new users who may expect an ENTER key to behave the same way as on other devices without surprises and implicit sideeffects. Also, Entry RPN resembles RPL in this respect, which makes it more reliably to use for users frequently switching between RPL and RPN calculators.
Thinking about it, I guess, the reason, why Entry RPN is more intuitive, is also down to how the postfix concept is taught in school or university (if at all). You first enter the arguments, then the operation. I have seen people failing to understand that you must press ENTER to input the first number, but, at least in Classical RPN, are not allowed to press ENTER to input the second number as well. It sounds arbitrary and illogical at first, until the reasons for why it was implemented this way are explained as well. It lacks the "symmetry", and recognizing inherited symmetries often makes it easier to learn something new (it's a bit about successful communication consisting of new information as well as redundancy).

Greetings,

Matthias