advantages of RPN

[Garth Wilson]

(05-21-2014 10:20 PM)Tugdual Wrote:  Interesting reading, thanks for sharing this. I personally don't value the number of keystrokes to distinguish RPN from other systems. It was interesting to see that if this number is always lower for RPN, it is not very different (<10%) and shall not explain all.

They did not compare to units with parentheses (like the TIs I started with); but even there, the comparisons in ads in the early 80's were sometimes invalid, for example:
(sin(n4^(n3*(n1+n2))))=
ignored the fact that the = key would close all the levels of parentheses at once, so a keypress count should not have included the )))).

However, the algebraic one cannot re-use intermediate parts of the equation without storing them in a variable for later retrieval; whereas with a stack, you can dup it. Things get hairy when you have lots of parts of a program needing temporary variables. Is a particular one free at the moment, or will I step on something still needed by a pending routine? It may be fine now, but what happens if I have to come back later and modify it? Did I document well enough which ones were used where, and when, or will it mess up and then a part I didn't touch quits working, because I used its temporary variable in my other modified routine? It can be a debugging nightmare. A stack reduces the need for variables, and makes program maintenance much easier. These temporary variables cease to exist when they're no longer needed.

Quote:What matters in my opinion is the user interaction during the calculation. With today calculator, I see kids entering the calculation, i.e. copying what they see on paper to screen and then press '=' or whatever key that performs the whole calculation and gives a result.

Educators fail to realize that this is not the usual situation in life though. In real life (I'm in EE), you usually don't have an equation in front of you on paper. You figure out what you need as you're punching buttons.