EE Pros: Is RPN still relevant?

[jakeisprobably]

I've been watching a few tutorials on the Forth programming language and looking into the history of calculators. Reverse Polish Notation seems, to me, to be more intuitive due to it's linear structure.
    For a new student just getting started, is it worthwhile to learn and utilize RPN in the professional world at this point?

[helius]

Learning to use a RPN calculator doesn't take long in any case, so not much time wasted if you decide it's not helping you.
In terms of the question in your topic, catenative programming languages are as relevant as they've ever been, and point-free style is used by the most modern languages (like Haskell).

[Benta]

For a new student just getting started, is it worthwhile to learn and utilize RPN in the professional world at this point?

Probably not.

I say this as an older guy possessing two HP-15C, one always in my jacket, the other on my workbench. Before finding the right App on the phone, or booting the laptop, I have an answer in seconds.

But I confess, it's nerdy.

Nowadays, starting a big simulator program for calculating an RC network seems to be the way to go.

[rstofer]

Absolutely!  The calculator I prefer to use, an HP48GX, uses ONLY RPN.  Some calculators use a mish-mashed RPN and some use either algebraic or text-book entry.

My grandson is taking Calc I and when we do the homework, we both use HP48GXs.  It is his preferred calculator after using HP Prime, TI Nspire and a couple of others.

It takes about 5 minutes to learn RPN, it just isn't a big deal.  Try (3+4)(5+6)/(4+5)*(7+8)
3 Enter
4 Plus
5 Enter
6 Plus
*
4 Enter
5 Plus
7 Enter
8 Plus
*
/

Now try it with something else!

I'm not an evangelist.  I use RPN and have for over 40 years.  Use it if you think it helps, skip it if you don't.

[helius]

Absolutely!  The calculator I prefer to use, an HP48GX, uses ONLY RPN.

Unless you type the ' key

[rstofer]

Absolutely!  The calculator I prefer to use, an HP48GX, uses ONLY RPN.

Unless you type the ' key

Oddly, I have never used that key!  Didn't even know what it did...

I have been using this calculator for 20 years or so and I still don't know what all the buttons do.  I did, however, program a fairly large Celestial Navigation program way back when.

[LaurentR]

Probably not useful. I was an avid RPN user during my school years, then the need for calculations dropped significantly and I learnt to use whatever was handy (e.g. the dreaded Windows Calculator) and it's just fine too. Being an EE doesn't add particular requirements (except needing conversions into binary or hex occasionally, for which RPN is neither better nor worse).

RPN feels right for a lot of quick mid-complexity operations, but for larger operations, nothing beats a nice pixeled LCD display and the whole operation displayed so that you can read it back and check it visually.

Regardless, you need to know how to handle the operator precedence so that you can either transcribe an existing formula into RPN or write a complex calculation into a normal calculator

It takes about 5 minutes to learn RPN, it just isn't a big deal.  Try (3+4)(5+6)/(4+5)*(7+8)
3 Enter
4 Plus
5 Enter
6 Plus
*
4 Enter
5 Plus
7 Enter
8 Plus
*
/

[claytonedgeuk]

I've been watching a few tutorials on the Fourth programming language and looking into the history of calculators. Reverse Polish Notation seems, to me, to be more intuitive due to it's linear structure.
    For a new student just getting started, is it worthwhile to learn and utilize RPN in the professional world at this point?

I learned rpn on one of the hp financial calculators....and when I needed a scientific going to an rpn was an easy choice. 

For me isn't just about the number of key presses but also about how my mind processes information, ie enter your two numbers and then do something to them (the rpn way)....rather than enter a number...prepare to do something to it...and here is the other number (the non rpn way).

I don't think it's a gimmick but as some others have said....its actually quite quick to learn....so easy enough to try and dump it if you don't like it.



Sent from my SM-G900F using Tapatalk

[David Hess]

I have replaced my HP48g with an HP50g and much prefer their RPN operating style.  One of the better features becomes apparent when people ask to borrow your calculator:

"Hey, can I borrow your calculator?"
"Sure, here you go."
*silence while calculator is inspected*
"Um, no thanks."

[CatalinaWOW]

Depends on what you do.  The last I knew, there were several programming languages that used RPN internally, and as pointed out above there are a few that present that face to the world. 

Calculators are mostly a dead end these days, and RPN has gotten quite rare in calculators so that wouldn't justify any real effort.

Unless you specialize in writing assemblers or compilers, or focus on one of the few RPN calculators available there really isn't much need to know RPN.

That said, it should take you 10-15 minutes to learn 99.9% of what you need in RPN.  Not much longer to become proficient in calculator operations.  The great thing about RPN is that it is totally consistent.  No need to memorize special rules for how to compute x to the y power as is usually the case with algebraic calculators.

Why not put it in your toolbox?

[eugenenine]

RPN is the only right way, you must learn RPN, all others are worthless .



RPN is more like how the microprocessor works, it makes it easy to work on a micro in assembly.

[w2aew]

Use whatever you're comfortable with. I used alegebraic through school (Casio Elsie-mate), but then got hooked on RPN at my first job in 1985. I've used an HP 15C ever since. Also have a 35S on my desk. I even balance my checkbook with a 32S.

[eugenenine]

I used to get magazines from the library with ads for hp calculators, it was like playboys for nerds.
I graduated high school and then 48sx was released and I worked and saved months for it and finally saved up the $300 and bought it from a store called service merchandise.  It was under glass like in a jewelry store so I made my purchase then went to the waiting room where the product you bought came out on a belt like luggage in the airport.  I almost cried when that little box finally came down the belt for me.

[djnz]

It's just calculator stuff... not really much to it imo.

These days I just have an ipython3 shell running all the time on my laptop...

[orolo]

Since you mention Forth, there is other family of languages where RPN is prominent: functional languages, like LISP, scheme, Haskell and the SMLs. These languages are not stack oriented, RPN emerges naturally from function composition. Most functional languages are flexible enough to allow the programmer to redefine most operators as infix, but I have found that the higher the abstraction, the more detrimental it is. For arithmetics it's ok; using monads with infix 'do' notation in Haskell just confuses me, even if there are people that swear it's easier.

RPN is the mathematical way of operating. First you get the operands, either in a stack, a tuple, or whatever. Then you apply some function, and get the result.

[kultakala]

I also started with a HP-41C back in the eighties and never had something else than RPN calculators.
It takes less key presses usually than an algebraic one, but i think the biggest advantage is that you have to understand the structure of the equation or whatever you are trying to calculate to be able to do it with an RPN calc.
On an algebraic thing you can blindly type in everything and when you did something wrong you dont know where, because you dont think first before using the calculator as you have to do with RPN.

[newbrain]

Do yourself a favor, download "free42" on your phone (fruit or robot), and if you want, to your desktop (fruit, non-flying bird or glazed hole in the wall).
It's a one to one emulation of one of the best (IMHO) HP calculators.

Just take some time with RPN, if you are a natural RPN guy it will "click in" very quickly, otherwise you'll hate it.
Of course, all the advanced functions take a long time.

As for the practical value...as much as I'd love to praise it, I don't think it's that much: apart from computer science, the only other exposure to RPN comes from HP calculators.

I learned rpn on one of the hp financial calculators.... 

Same here: this one (this might show my age...I was just a kid, I swear!).
I was able to calculate logs/exp with the financial functions!

It's been a kind of imprinting, and I have always had problems with algebraic calculators, as they have all slightly different syntax (even the same brand!).
I'm actually evaluating getting a new HP35S...

[frozenfrogz]

Funny you are asking this today, as I started a thread on my own about buying an HP 16c.
Having a calculator handy is very much essential to me, though I would not need it every day. For me, it is most convenient to have it sitting on my desk for whatever task comes along instead of using a software based solution - just like notes on real paper work best for me.

RPN is fun to use apart from being faster and more natural than working with brackets. There is, however, something very nerdy about it xD

[TNorthover]

RPN is the mathematical way of operating. First you get the operands, either in a stack, a tuple, or whatever. Then you apply some function, and get the result.

That's a bit of a stretch. There's no notion of a stack in conventional mathematics, and the notation is definitely infix.

If I had to say any paradigm was "the mathematical way" I'd go for declarative, like prologue. A mathematical expression representing a series of constraints on the variables involved that may or may not uniquely determine a result.

[David Hess]

Besides being faster and ultimately easier to use, I like RPN for the stack which holds, and in the case of the HP48g and HP50g, displays multiple results.  I prefer a calculator over using a PDA/phone or computer because it is portable, the battery life is effectively unlimited, and the interface is better.

While the HP50g has many improvements over the HP48g, it is a step back as far as user interface performance (it is several times slower) and the PDA/phone calculator programs I have tried except for my old Palm Pilot are even worse.

[orolo]

That's a bit of a stretch. There's no notion of a stack in conventional mathematics, and the notation is definitely infix.

If I had to say any paradigm was "the mathematical way" I'd go for declarative, like prologue. A mathematical expression representing a series of constraints on the variables involved that may or may not uniquely determine a result.

Any basic algebra textbook will define addition of real numbers as a function from the cartesian product of the real numbers into themselves \$+ : \mathbb{R}\times\mathbb{R} \longrightarrow \mathbb{R}\$, taking a couple numbers into their sum. That is, addition takes a tuple of reals into a real number. Taking a tuple is essentially the same as taking a couple of elements from the top of a stack. When one uses infix notation, one is implicitly currying the addition function, which is in fact stretching its algebraic definition.

[Elf]

Ah, this thread made me nostalgic for the HP 42s I used to use. I went looking to see if you can still get them, but they seem to go for hundreds of dollars now, and it seems that HP's recent (although now decade old) engineering efforts with the 35s have been disappointing.

Instead I bought a SwissMicros DM15L clone of the HP 15C.

[claytonedgeuk]

When the Swissmicros shows up...can you report back?  I don't think there is even any attempt to conceal the inspiration...but would be keen on hearing how well it matches up.

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[Elf]

When the Swissmicros shows up...can you report back?  I don't think there is even any attempt to conceal the inspiration...but would be keen on hearing how well it matches up.

Sure!

[Gyro]

Besides being faster and ultimately easier to use, I like RPN for the stack which holds, and in the case of the HP48g and HP50g, displays multiple results.  I prefer a calculator over using a PDA/phone or computer because it is portable, the battery life is effectively unlimited, and the interface is better.

While the HP50g has many improvements over the HP48g, it is a step back as far as user interface performance (it is several times slower) and the PDA/phone calculator programs I have tried except for my old Palm Pilot are even worse.

As mentioned in the HP16C thread I still use NEOCAL on my old Palm TX. It can be set to display 4 lines of the RPN stack (X,Y,Z,and T) though you can set the stack deeper than that. It does algebraic too, so you don't see RPN in most of the screenshots.

I believe the free lite version for Android has the same capability, though misses out on programmer, Financial, etc. functions. I haven't tried it myself, I have a Nokia 3310 (Hey, I'm trendy again  )

http://www.hudren.com/products/neocal/