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Peter Klein · 12-19-2023, 07:42 AM

Why do I prefer RPN? Because in the mid-70s, after using a simple four-banger, I got an RPN-based Novus/National Semiconductor "Mathematician." It took me all of 10 minutes to learn RPN. I loved it and never looked back. When I found out about the programmable HP-25, I bought one.

I think there are two key aspects to HP calculators: RPN, and the quality of design and manufacture. The latter includes the feel of the keys, which I think is a major part of the appeal to many of us.

I can use an algebraic calculator, awkwardly, but I prefer RPN. Perhaps if my first scientific had been an algebraic machine, I would prefer that now. But though I started with a simple algebraic machine, something about RPN resonated with me, and said, "this is for you."

As for relevance, there's mass market relevance, as in, "we can sell this to everyone." Then there's the relevance of a tool that a certain subset of people like and want to use. Economy of scale means that a niche product is going to be more expensive. But it's still relevant enough that RPN products are made.

Perhaps the best indication of RPN's relevance is the number of HP simulators for mobile devices. Surely not everyone who buys them are doing so out of nostalgia.

If you want coffee, you can use a generic coffee maker, or you can use an espresso machine. RPN calculators are the equivalent of espresso machines.

Peter Klein · 12-19-2023, 07:54 AM

(12-18-2023 11:00 AM)carey Wrote: ...how my mind works, which is to put the numbers in my line of sight and poke them until they tell me what I want.

This! Years ago, I told a relative of mine that I preferred RPN calculators. He made a crude joke, saying it was called Reverse Polish Notation because it was backwards and stupid. I told him that it was neither. I said that RPN made it easy to solve problems in the order that we actually solved them ourselves, as opposed to the way the formula was written on paper. But also, since I was not perfect, I sometimes initially entered numbers in the "wrong" order. No problem. I could easily rearrange a couple of terms and solve the problem without having to enter everything all over again.

Here's to us "pokers."

--Peter

Maximilian Hohmann · (This post was last modified: 12-19-2023 10:50 AM by Maximilian Hohmann.)

Hello!

First, let me please say this to everyone who contributes here: I really enjoy this thread because it is about the very essence of why I spend so much time and money for calculators. What is it that attracts us/me to certain models and why does the same not apply to every other human being? And this is the real question here! Not I you or I like RPN, but why did so few other people like it, so that it is now on the verge of disappearing? And can anything be done to resurrect it?

What I also like in this thread - and in any other by the way - are the off-topics like this:

(12-19-2023 03:14 AM)Thomas Klemm Wrote: Charging time of electric vehicle: 0.75409h

Thomas, I guess you have not driven an electric car yet ;-) Computing the range and charging time is not an exact science. You can discard 4 of your five decimal places or easier still, do the entire calculation mentally with just integer numbers!
Lots of traffic on the road so that you can only do an average of 60km/h -> 30km more range. No traffic on the road so that you can do an average of 100km/h -> 50km less range... Your wife says "it's cold in here" so you turn up the temperature by 3 degress and switch on her seat heater -> 40km less range.... You come to your car and find the windscreen frosted over. No need to scrape that off or wait till the engine is warm enough to melt it in an electric car - just turn on the electric windshield heater and defroster and two minutes later the car is warm and the windows are clear. I can even do that from my mobile phone remotely. Pure magic and one of the reasons why I will never ever want to drive a petrol car again. But it comes at a cost: 25km less range...
During summer (say June to October, because I only got it in June) our car consumed electricity at a very constistent rate 12,8kWh/100km. Now in winter it varies between 14 and 20kWh/100km, and quite unpredictably so. Not a mathematical task that requires decimal places!

Regards
Max

Maximilian Hohmann · (This post was last modified: 12-19-2023 11:23 AM by Maximilian Hohmann.)

Hallo!

(12-19-2023 12:10 AM)John Garza (3665) Wrote: And I'll say it again, the education system is to blame. You do NOT specify the actual products. You only specify the REQUIREMENTS of the product. Other than the appearance of brand favoritism and perhaps under the table bribery, choosing a tool is a personal decision. I would never tolerate someone telling me or my kids what specific machine to use. That's like telling kids what brand of pencil to buy. Crazy.

"Andere Länder, andere Sitten" ("other countries, other manners") is a famous proverb here. My wife teaches art at a german "gymnasium", which would be something between high school and college in the United States. Here in Germany, education is completely free of charge - from primary school all the way hrough university till postgraduate studies - and open for everyone, be it children of millionaires or refugees from Syria who own nothing but the clothes they wear. This means that expensive tools, like the special pencils and colours used in art classes, are provided by the school. Free of charge for every student. But this of course means, that in order to guarantee equal chances to all children, only the tools provided by the school can be used. So you can give your child every pencil that you like and he or she can use it as he or she likes, but not in classes where tools are provided.

And the same applied to calculators when they started to become affordable and schools decided that they could be useful teaching aids. They were provided by the school free of charge to the pupils. On eBay one can occasionally find "class sets" of calculators, constisting of a briefcase with built-in power supply and charging slots for 20 or 30 calculators. These were distributed by the math or physics teacher at the beginning of the class and collected for recharging at the end (interestingly, this was similar in capitalist western Germany and communist eastern Germany!). Of course schools did not, and could not, buy the most expensive calculators on the market (HP) for that purpose. Instead they went for locally produced models in the medium price segment, often "Aristo" (made by Dennert&Pape) or "Triumph Adler". Only when calculators became really cheap and affordable to everyone at the end of the 1980ies they were no longer provided by the schools. But recently, this practice has reappeared with tablets.
So if HP had been able to provide an affordable basic scientific calculator, like maybe an HP-21 at 1/3 of it's price, in 1977 this might have become the "school calculator" in Germany and everybody would be talking RPN ever since!

Regards
Max

Hans S. · 12-19-2023, 06:09 PM

Maximilian, even if this is 1) off-topic and 2) about cars = the direct path to the next general carnage, I would like to make the following comment.

You write: >>You come to your car and find the windscreen frosted over. No need to scrape that off or wait till the engine is warm enough to melt it in an electric car - just turn on the electric windshield heater and defroster and two minutes later the car is warm and the windows are clear. I can even do that from my mobile phone remotely. Pure magic and one of the reasons why I will never ever want to drive a petrol car again. But it comes at a cost: 25km less range.<<

That's exactly what my petrol-powered car can do. It's called auxiliary heating, no magic at all. The only difference: the range was greater than 1000 km before and is greater than 1000 km afterwards. In my job, I was sometimes forced to drive electric cars, and my personal conclusion is: never again.

Best regards,

Hans

Maximilian Hohmann · 12-19-2023, 06:56 PM

Hello Hans!

(12-19-2023 06:09 PM)Hans S. Wrote: That's exactly what my petrol-powered car can do. It's called auxiliary heating, no magic at all.

Yes, I know. But in my previous cars this option was either not available or insanely expensive. With my electrical car it came for free.

(12-19-2023 06:09 PM)Hans S. Wrote: In my job, I was sometimes forced to drive electric cars, and my personal conclusion is: never again.

Interesting! It probably very much depends on the type of driving one has to do. I must admit that for german motorways an electric car is not the best option. The crazy rat-race without speed limit going on there depletes the batteries in no time. Therefore I avoid the motorway as good as I can, but I already did that in my petrol days. For everything over 100km, both private and for work, I usually take the train.

Regards
Max

Peet · 12-19-2023, 07:50 PM

Unfortunately, RPN never had relevance for most people and the education system, but there was always a group of people who found this input method relevant.

For me, RPN will remain relevant as long as I use calculators (physical or virtual) to do calculations. It is and remains the more comfortable input method for me.

ctrclckws · 12-19-2023, 08:04 PM

I have fun with either algebraic, or RPN. Have not used RPL enough to have an opinion.

My needs are satisfied mostly with a basic 4 operation calculator.

My HP journey started with the 12C and 15C, only recently did I learn about the other Voyagers.

My first scientific calculator was in 77-78, an original TI-30, long gone.

I just wish I had time and reason to use these wonderful tools to their limits.

dm319 · 12-19-2023, 08:31 PM

(12-19-2023 10:45 AM)Maximilian Hohmann Wrote: I really enjoy this thread because it is about the very essence of why I spend so much time and money for calculators.

Me too! This is a really fun thread. It is nice that we have assembled here in an obscure corner of the internet to debate the relevance of an unpopular notation (RPN) on a dying platform (pocket calculator)!

(12-19-2023 10:45 AM)Maximilian Hohmann Wrote: And can anything be done to resurrect it?

We need:
1. A cheap RPN scientific that is palatable for kids and meets school/exam requirements
2. A worldwide lobbying group / cult that continually promotes the benefits of RPN in education.
3. Children that want to use it.

(12-19-2023 03:14 AM)Thomas Klemm Wrote: Thus I assume that our results agree.

Yes, I always do a 1.1x to give me a bit of leeway. If you aim to arrive home with exactly 0%, for one thing the power progressively disappears as you approach your drive, which is disconcerting, and secondly, any slight variance or detour and stress levels can rise...

(12-19-2023 10:45 AM)Maximilian Hohmann Wrote: Computing the range and charging time is not an exact science.

True, but I think we can be more accurate than the car computers often suggest. They really have no idea IMO. As a ballpark, my afternoon commute is very similar in terms of consumption to my morning commute (as it is over similar road), so that is a good guide. I use my calculator if I'm either being 1. stingy with how much electricity I'm paying for or 2. impatient charging en-route on my way somewhere. You should try it! I have a very useful solver-like program which is very quick. Maybe your mental arithmetic is better than mine though.

(12-19-2023 02:51 AM)avsebastian Wrote: They hate the HP calculator, especially the use of the RPN.

I always thought finance people and RPN were strange bed fellows. I suspect that the 12C arrived at its position not by virtue of being RPN, but despite that because of its accuracy. It has such a terrific UI for 'solving'. Ingenious to use the concept that if you press two variables in a row, then you are indicating you want it to solve. However, it feels a bit of a black box until you realise that is how it works (I was an idiot for a while and thought the 12x and 12/ buttons just did that - times and divide by 12, which really really confused me). I bet you a number of finance people in the 80s/90s used it just to get the values, then used an algebraic calculator for subsequent calculations.

What is so great about the solvers on HPs is that you use it within the calculator UI. Which means that the answer is usable straight away. That seems to go nicely with RPN.

I tried the TVM interface on the TI-83+ recently (in my ongoing bid to create a cheap RPN calculator courtesy of bxparks), and it is terrible! I have to navigate to each variable, type in the value, and then to solve it I must find a tiny 'solve' writing which needs a modifier key. If figure if it is going to be so much less efficient, it should at least be really obvious. And I can't seemingly use values I calculated in the calculator, nor can I use the solved values back in the calculator.

(12-19-2023 07:54 AM)Peter Klein Wrote: Here's to us "pokers."

Hear hear! - a fellow poker.

Matt Agajanian · 12-19-2023, 08:32 PM

(12-18-2023 09:23 AM)Garth Wilson Wrote:
(12-18-2023 07:56 AM)carey Wrote: However calculations aren't done by hand anymore

I guess you live in a world different from mine.

Quote:so there's no need to mimic hand calculations and RPN's intuitiveness with numeric operations is offset by RPN's torturousness when working with equations without numbers.

Only a small part of programming is math and equations though.

Quote:(imagine writing words in a sentence backwards).

It is my understanding that some spoken languages are indeed RPN, like that where we would say "put on shoes," in Korean it comes out more like "shoes, install."

I have always explained RPN in this context. You can easily use English to explain RPN.

I’ll run in the New York Marathon five minutes from now.
Five minutes from now I’ll be running in the New York Marathon.

Matt Agajanian · 12-19-2023, 10:22 PM

(12-19-2023 07:50 PM)Peet Wrote: Unfortunately, RPN never had relevance for most people and the education system, but there was always a group of people who found this input method relevant.

For me, RPN will remain relevant as long as I use calculators (physical or virtual) to do calculations. It is and remains the more comfortable input method for me.

That makes two of us. Looks like I'm in good company.

carey · (This post was last modified: 12-20-2023 07:38 AM by carey.)

(12-19-2023 08:32 PM)Matt Agajanian Wrote: I have always explained RPN in this context. You can easily use English to explain RPN.

I’ll run in the New York Marathon five minutes from now.
Five minutes from now I’ll be running in the New York Marathon.

Good example for explaining RPN, however, a more relevant example for comparing RPN equation entry to algebraic equation entry (my point that the comments quoted in your post were replying to) might be to compare the quadratic formula in any RPN listing (e.g., https://www.hpmuseum.org/software/15quad4.htm) to algebraic entry.

Unlike algebraic entry, the quadratic formula isn't immediately recognizable in RPN, but perhaps fun to decipher. :)

MikeSD · (This post was last modified: 12-20-2023 05:06 PM by MikeSD.)

(12-17-2023 06:50 AM)Matt Agajanian Wrote: Hi all.

I’m gonna say yes. Since there’s SwissMicros, Panamatik, the developers of WP34S.

In addition, for the smartphone, there're Cuvee, the GO-2x series, i41CX. Plus, our beloved 15C has been resurrected.

I'm 78 and I was around when the first modern caculators appeared. And I'm still a full-time, working, engineer. I started with the HP-35.

I doubt I ever used an algebraic entry calculator, for anything but to try out. I still use RPN calculator today. I use an emulated HP-41CX on my phone. Although I have the real thing too.

The thing about algebraic calculators is you can take two different calculators, enter an equation the same way on both, and becaues each may handle parns differently, come up with two entirely different answers. I never got past that.

RPN always gives the same answer, no matter which one you use. To me, that's very relevant.

Garth Wilson · 12-20-2023, 10:24 PM

(12-19-2023 08:32 PM)Matt Agajanian Wrote: I have always explained RPN in this context. You can easily use English to explain RPN.

I’ll run in the New York Marathon five minutes from now.
Five minutes from now I’ll be running in the New York Marathon.

In Spanish, the word order would be switched to "Marathon New York."

Garth Wilson · 12-20-2023, 10:26 PM

(12-18-2023 03:18 PM)bxparks Wrote:
(12-18-2023 12:08 PM)ijabbott Wrote: Indeed, a four-level stack is an artifice that has no place in teaching or learning mathematics. The NSTK mode opens other avenues, such as thinking about how computers work internally.

I find the traditional 4-level RPN stack works for me because I can keep track of 4 things in my head pretty easily.

Same here. I have no need for a four-line display to show what's in the stack registers. If you can't keep track of them, a display might not be of much use anyway, because it'll show you numbers but not tell you what each number is.

Quote:Beyond 4 levels, [...] it makes programming in a stack-based language like Forth frustrating. (RPL seems very similar to Forth as far as I can tell.)

The following is slightly edited from a stacks article on my website.

Comments should prevent the possibility of confusion of what's on the stack. Sure, I've seen very unreadable source code in Forth, but I blame that on the programmer, not the language. I've seen horrid source code in the other languages I've worked with, too.

Garth Wilson · 12-20-2023, 10:27 PM

(12-18-2023 11:00 AM)carey Wrote:
(12-18-2023 07:56 AM)carey Wrote: However calculations aren't done by hand anymore

(12-18-2023 09:23 AM)Garth Wilson Wrote: I guess you live in a world different from mine.

If you are claiming to do most calculations with paper and pencil (which is obviously what I meant by "calculations aren't done by hand anymore" as I spoke of RPN mimicking hand calculations (and a handheld calculator is a machine), then yes, I live in a different world from yours!

Not particularly by hand with pencil on paper; but when I'm designing circuits, I definitely have the calculator nearby, and pick it up often, and work it without equations in front of me.

Quote:
(12-18-2023 07:56 AM)carey Wrote: so there's no need to mimic hand calculations and RPN's intuitiveness with numeric operations is offset by RPN's torturousness when working with equations without numbers.

(12-18-2023 09:23 AM)Garth Wilson Wrote: Only a small part of programming is math and equations though.

If we're talking about RPN programming on a calculator (this thread?), and your experience is that only a small part of that programming is math and equations, then you're living in a different world than mine

Much of programming is logic, strings, and things other than equations. The entire reason I got into HP-41 was HP-IL and the ability, through the HP82169A HPIL-to-IEEE488 interface converter, to control and take data from equipment on the workbench. Up to that point I had only been using algebraic calculators, most intensely my TI-59, writing programs that overflowed its memory and needed cards fed to to it at various points, kind of like disc-swapping. I found the HP-41's RPN to be very natural though, and quite suitable for forming the command strings to send to the workbench equipment. (This was before laptops, and I sometimes didn't have room on the workbench for a laptop anyway.)

(12-18-2023 07:56 AM)carey Wrote:
(12-18-2023 09:23 AM)Garth Wilson Wrote:
(12-18-2023 07:56 AM)carey Wrote: (imagine writing words in a sentence backwards).

It is my understanding that some spoken languages are indeed RPN, like that where we would say "put on shoes," in Korean it comes out more like "shoes, install."

The fact that it was necessary to select a language (Korean) which most English-speakers find difficult to learn for an example of backwards wording seems only to prove my point. The comparison of writing equations backwards to backwards wording was only an analogy. More relevant, modern Korean is written left to right like English, yet you will not find Koreans writing equations backwards.

What I meant was that maybe a reason you think RPN is harder is partly because your native spoken language is not RPN, while native speakers of a language that is RPN (like Korean apparently is) would find RPN calculators more natural. But there you go again, talking about "writing equations." Part of what I'm saying is that in the case of many of the calculations we do in engineering, we don't start with an equation in front of us. We go through it without ever looking at, or writing, an equation.

carey · (This post was last modified: 12-21-2023 01:33 AM by carey.)

Hi Garth,

All good points that you make!

I agree with you that in a data-driven or control engineering environment, RPN shines. FORTH, which uses RPN and was created shortly before the HP-35, began as a control language for radio telescopes. After learning RPN on the 15C in the 1980's I started using FORTH in embedded systems.

Yes, RPN works great with data (whether numbers, logic or strings), less great with equations.

Valentin Albillo · 12-21-2023, 02:17 AM

.
Hi, all,

For those of you interested in the OP ("Is RPN still relevant?"), here you are, two previous threads on this same subject, also by Mr. Agajanian:

Is RPN still relevant? (5th October, 2015)

RPN/RPL is still relevant (8th April, 2014)

And for those interested in the RPN vs RPL subject, which has been mentioned in this very thread and in a zillion previous ones, these are a few worthwhile historic ones:

HP Thread VA002e - RPN/RPL - What? (9 June 2003)

HP Thread VA100b - How many stack levels ? (15 July 2005)

HP Thread VA103b - RPN or RPL (15 Feb 2006)

HP Thread VA103c - Sample problems to evaluate RPL vs RPN "objectively" (21 Feb 2006)

"Nihil novi sub sole" (Ecclesiastes 1:9)

V.

Maximilian Hohmann · (This post was last modified: 12-21-2023 02:01 PM by Maximilian Hohmann.)

Hello,

(12-21-2023 02:17 AM)Valentin Albillo Wrote: "Nihil novi sub sole" (Ecclesiastes 1:9)

I have to object to some degree, because since Matt posed his question for the first time 9 years ago and since you asked the question about the number of stack levels 18 years ago, a significant change in demographics must have taken place on this forum. Tempus fugit...

And therefore, it would be interesting to compare the results of this discussion then and now. My feeling, without having done an analysis yet, is that the number of answers like "RPN is not relevant in 2023" is higher than I would have thought. Maybe people are just braver now :-)
Which is no wonder at all, because the people who first came in contact with RPN pocket calculators in 1972 are two generations behind the students of our days (my father vs. my son!). And as we know, RPN turned out to be a kind of flash in the pan that lasted half a generation at most.

Regards
Max

**rprosperi** · 12-21-2023, 01:27 PM

The incomplete question "Is RPN still relevant?" is simply not clear enough for any kind of consensus, as the disparate and diverse replies show.

Is RPN still relevant for the public at large?

Is RPN still relevant for high-end calculator users?

Is RPN still relevant for readers of this MoHPC Forum?

Is RPN relevant for American (or substitute UK, EU, China, Indonesian, 3rd-world, etc.) school children?

are all questions that might reasonably be debated, likely with differing conclusions, but as initially asked is so wide open as to be impossible to reach a conclusion. Which is not necessarily bad, as the various replies and sub-threads above are and can be interesting too, but it makes for a complicated thread to wade through with 5 or more different topics or aspects all being discussed together, often conflicting with each other and leading to reader confusion.

Valentin's typical complete analysis of the history of this topics illustrates well that this is broadly a topic which is near and dear to most of our hearts, and never lacks comment or debate.

My own view is the question is irrelevant... for me. I like and use RPN daily, but I also like and use RPL, albeit slightly less often. These are tools I use in my day-to-day tasks, just like other problem solving techniques. I frankly don't care what other people use from a right or wrong perspective, but I remain interested in continuing to learn more about how these tools can be sharpened and used for more tasks.

So... please carry on.... Smile