advantages of RPN

[Garth Wilson]

(05-22-2014 09:44 AM)Nigel (UK) Wrote:  

(05-22-2014 01:25 AM)Garth Wilson Wrote:  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.

I like RPN a lot, but my Prime is set to algebraic mode. What I like so much about algebraic mode on the Prime (and on calculators like the TI NSpire, TI-89, etc.) is that there is a visible and re-usable history of all calculations. I virtually never need to use variables to store results because previous results - and the calculations that led to them - are always available.

What I meant was when you need a portion again in the same equation, like (a+b)/(a+b+c) for a simple example.

Alvaro Wrote:Let me say like this: There are much better options.

If the HP50g had a BASIC language on it I am sure it would be the "Ultra Calculator of the Century".

My personal opinion is that it will be very difficult to find something worst than UserRPN as a "programing Language".
While I agree that for manual calculations there is some advantage of PRN, I even like it, but as a "Programing Language" is the worst I can imagine.

UserRPL is very difficult to read, to follow.
UserRPN makes heavy usage of the stack. So, while READING or PROGRAMING you have to do a big effort to follow what is happening on the Stack what makes it much difficult to read, besides the huge usage of all sort Brackets.

Not forgetting the unpossibilty of programing on a Desktop PC, run it there and transfer the ready Programm to the HP

I disagree of the advantage people are saying about "user interact" with stack. For me that is something like "marketing".

I have two HP-71's, which, with the math module and the LEX file contributions from the users' groups, have by far the best BASIC I've ever seen; yet for math-type programming, I still prefer the 41. I write the programs in a text editor on the PC though, so I can group associated instructions on a line, indent loops, add comments, etc., before keying them into the 41. Then they usually work on first try, unlike the situation with the 71. When I try to do things on the 71 in BASIC, my debugging partly consists of counting parentheses to figure out why it didn't like what I typed in. It can be a bit difficult sometimes. I'd rather do it in RPN, and I have no trouble keeping the image of what's happening on the stack in my mind. Even my assembly-language programming for microcontrollers for commercial products is becoming RPN-like, with stacks. I really don't want any more algebraic languages. I'm done with them. People don't all think the same; but although different languages might me more natural or unnatural for different people, I think people can gain skill in something that was previously unnatural. I understand RPN is very natural for native Korean speakers, because their spoken language is very RPN.