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mcg
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04 Dec 2010, 12:00 am

Does anyone else use HP (or other RPN) calculators?

RPN saves so many keystrokes and just feels way more natural than using awkward parentheses on an algebraic calculator.

The 80s and early 90s models were pretty much the pinnacle of quality and usability in handheld calculators.

The HP 41CV is one of my favorites:
Image

Probably one of the best possible key layouts for a keystroke programmable calculator, and pressing them gives the most amazing feeling (it's hard to explain, but anyone who has used one will tell you). This thing also has amazing build quality. The key labels are injection molded all the way through the key so that they never wear off, even after years of use. It's also way more easily repairable than any recent calculator, on the off chance it breaks on you.

The RPL graphing ones with the infinite stack are alright too, but they always throw me for a loop because I'm so used to using the roll down and x <> y operations to solve problems. The keys don't feel as good as the older ones, although they are still way above average.

No modern calculators can even hold a candle to the old HPs. The TI-89 is a great example of a sh***y calculator. The trig functions are all shifted so you need two keystrokes to use them, and there's no inverse function (at least on the keypad). It's pretty much designed specifically so math students can type in problems exactly as they appear in the textbook and magically get an answer. If you are using it for routine calculation the key layout just slows you up.

I don't know what I would do if one of my HPs got lost or broke. When I'm in public I use an old soviet MK-61 because it has RPN and you can get them for super cheap on ebay (it would cost hundreds of dollars to replace my HP 41CV).



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04 Dec 2010, 12:04 am

I played with a HP48G a few times. I need to pickup an HP10 series calc for a finance class next semester.



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04 Dec 2010, 12:21 am

Don't mess with Texas Instruments. The integrated CAS and other powerful features are what make the TI-89 the best calculator on the market. Besides that, RPN is clumsy and awkward.


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DNForrest
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04 Dec 2010, 12:25 am

I don't even use a calculator anymore (save for the occasional exam), I just do everything in Excel.



mcg
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04 Dec 2010, 12:33 am

The HP 50 has a CAS and other powerful features, including a C compiler for its powerful ARM processor (it needs to be powerful, since most of the code is old HP 48 code running on an emulated Saturn, haha). Also, it's buttons don't feel like they are just jiggling around loose in their little sockets. They only have one degree of freedom, in the direction that you are supposed to press them.

Once you master it, RPN is extremely elegant and saves you lots of keystrokes (even compared to an algebraic calculator with a better key layout than the TI-89, like almost any other calculator on the market).

What's an example of a problem for which RPN is clumsy and awkward?



Last edited by mcg on 04 Dec 2010, 12:47 am, edited 1 time in total.

mcg
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04 Dec 2010, 12:35 am

nthach wrote:
I played with a HP48G a few times. I need to pickup an HP10 series calc for a finance class next semester.
Ah, the 48G is a good calculator (I have two of them). The screen contrast sucks, though.

Does your finance calc have to be a 10 series? Because the 12 is a great little calculator, and is native RPN.



Orwell
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04 Dec 2010, 1:45 am

mcg wrote:
The HP 50 has a CAS and other powerful features, including a C compiler for its powerful ARM processor (it needs to be powerful, since most of the code is old HP 48 code running on an emulated Saturn, haha).

In what universe is a 203MHz processor underclocked to 75MHz "powerful?" TI has badly under-specced calculators as well, but calling that processor "powerful" is silly. The TI-89 Titanium with its grossly under-powered 16MHz Motorola 68k processor still outperforms the HP50 CAS for almost all common operations. And HP really has nothing to stand head-to-head against the Nspire.

And who writes C on their calculator? If you're doing something complex enough that you need to use a "real" programming language like C, you'd be writing it on a PC, not a calculator.

Quote:
Once you master it, RPN is extremely elegant and saves you lots of keystrokes

RPN users are a cult, just like Dvorak keyboard fanatics. My dad uses and likes RPN (he's an aerospace engineer) but I don't see the benefit. At best you save a couple keystrokes. I don't think the extra learning curve is worth saving one or two keystrokes.

Quote:
What's an example of a problem for which RPN is clumsy and awkward?

Any problem. Addition of two numbers. Why do you have to hit "enter" contantly? The whole process is counterintuitive and goes against standard mathematical notation.


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mcg
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04 Dec 2010, 3:01 am

Orwell wrote:
mcg wrote:
The HP 50 has a CAS and other powerful features, including a C compiler for its powerful ARM processor (it needs to be powerful, since most of the code is old HP 48 code running on an emulated Saturn, haha).

In what universe is a 203MHz processor underclocked to 75MHz "powerful?" TI has badly under-specced calculators as well, but calling that processor "powerful" is silly. The TI-89 Titanium with its grossly under-powered 16MHz Motorola 68k processor still outperforms the HP50 CAS for almost all common operations. And HP really has nothing to stand head-to-head against the Nspire.

Powerful for a handheld calculator (not that a handheld calculator needs to be that powerful). And you can clock it up if you don't care about battery life. I've never used an Nspire but just looking at it, it looks really painful to use. No trig functions on the keypad, for example.

Orwell wrote:
And who writes C on their calculator? If you're doing something complex enough that you need to use a "real" programming language like C, you'd be writing it on a PC, not a calculator.

It's a cross compiler, so you would probably want to write the code on your PC. But when it comes to writing programs on the calculator, RPL is a really expressive language (like postfix LISP) and really fast and simple to enter into a calculator. Personally I hardly ever use graphing calculators (only for math classes). I actually prefer the ones with the 4-level stack because for most of the stuff I would use a calculator for, because of the swap and roll down keys. And they're not as big and clunky. Usually, if I needed a symbolic CAS I would just use MathCAD.

Orwell wrote:
Quote:
Once you master it, RPN is extremely elegant and saves you lots of keystrokes

RPN users are a cult, just like Dvorak keyboard fanatics. My dad uses and likes RPN (he's an aerospace engineer) but I don't see the benefit. At best you save a couple keystrokes. I don't think the extra learning curve is worth saving one or two keystrokes.

Haha, my dad is an aerospace engineer, too. I've been using HP calculators since the very beginning so it has always seemed pretty intuitive to me. One of the benefits is really simple, fast, and powerful keystroke programming. Another is never having to write numbers down on paper or store them in variables. It's also good for multi-step calculations where you want to see an intermediate result.

Orwell wrote:
Quote:
What's an example of a problem for which RPN is clumsy and awkward?

Any problem. Addition of two numbers. Why do you have to hit "enter" contantly? The whole process is counterintuitive and goes against standard mathematical notation.

You only have to hit enter once to add two numbers: 2 [enter] 5 [+]



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04 Dec 2010, 3:46 am

Orwell wrote:
In what universe is a 203MHz processor underclocked to 75MHz "powerful?" TI has badly under-specced calculators as well, but calling that processor "powerful" is silly. The TI-89 Titanium with its grossly under-powered 16MHz Motorola 68k processor still outperforms the HP50 CAS for almost all common operations.

In this universe in the mid-90's when the fastest desktops available were that speed or slower.

Whether you're talking about computers or calculators, speed is relative. 75Mhz is absolutely blazing compared to the first computer I programmed on, which had a turbo button that would double its clock speed to a zippy 12Mhz.

Quote:
And who writes C on their calculator? If you're doing something complex enough that you need to use a "real" programming language like C, you'd be writing it on a PC, not a calculator.

Anyone who knows C and needs to (or wants to) program something in a calculator. I've seen some pretty crappy calculator programming languages, C is a big step up.

Your argument, by the way, is a good argument against using calculators at all for certain problems. It isn't specific to C, RPN, or HP.

Quote:
At best you save a couple keystrokes. I don't think the extra learning curve is worth saving one or two keystrokes.

*shrug* It's up to you what you think is worth learning or not. But if you're going to say that it isn't worth learning for anyone, maybe you should pay attention to all of the people who did learn it, and thought it was great.

Quote:
Quote:
What's an example of a problem for which RPN is clumsy and awkward?

Any problem. Addition of two numbers. Why do you have to hit "enter" contantly?

Why do you have to hit "equals" constantly on a non-RPN calculator? Same reason. To tell the calculator that you're done with whatever number you're inputting at the moment.

And, so you know, you don't have to hit it all the time on an RPN calculator. You only need to do it once, to separate the first 2 numbers you're entering, every other related calculation only makes you press the number keys and the operations. It's the non-RPN calculators that have a disadvantage here, since you actually do have to press equals a lot.

Quote:
The whole process is counterintuitive

The process is extremely intuitive. Once you actually know how it works.

Quote:
and goes against standard mathematical notation.

How?


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04 Dec 2010, 4:34 am

mcg wrote:
nthach wrote:
I played with a HP48G a few times. I need to pickup an HP10 series calc for a finance class next semester.
Ah, the 48G is a good calculator (I have two of them). The screen contrast sucks, though.

Does your finance calc have to be a 10 series? Because the 12 is a great little calculator, and is native RPN.

I do not know. I need to get the syllabi first. I'd want to learn the RPN.

I have the HP48G whenever the real nerd in me comes out. I use my TI-84 Plus Silver Edition for my calculating needs when my iPhone can't/won't do it. Supposedly HP and TI do sell apps in the App Store that emulates many of their calculators.



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04 Dec 2010, 11:43 am

Ancalagon wrote:
Whether you're talking about computers or calculators, speed is relative. 75Mhz is absolutely blazing compared to the first computer I programmed on, which had a turbo button that would double its clock speed to a zippy 12Mhz.

The TI Nspire has a fairly similar processor to the HP50. But the 89 Titanium has a much weaker processor and yet outperforms the HP50 for most tasks. Someone is doing something wrong over at HP on the software side.

But both companies are selling very underpowered machines for the cost. A similarly priced cell phone nowadays will often have a better processor. The price-to-performance ratio for high-end calculators has not significantly improved in the past decade, despite all the advances in computer hardware.

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Anyone who knows C and needs to (or wants to) program something in a calculator. I've seen some pretty crappy calculator programming languages, C is a big step up.

Your argument, by the way, is a good argument against using calculators at all for certain problems. It isn't specific to C, RPN, or HP.

Correct. Text editing on a calculator is miserable, simple due to the fact that it doesn't have a full keybaord (the Nspire has a qwerty keyboard, but it's too small to be comfortably used). At the most you'd write a very short program on your calculator, and for such things it doesn't matter much what language you use. If you're writing anything serious, you need to be on a proper PC to do it. My point was just that support for C isn't a meaningful selling point.

A good selling point for TI calculators would be the large number of applications available for it. Of course we all know the various games (Zelda, Mario, Tetris, Phoenix, etc) but it also has several chess programs, which is nice, and a number of programs for doing "real" work, such as additional math aids.

Quote:
*shrug* It's up to you what you think is worth learning or not. But if you're going to say that it isn't worth learning for anyone, maybe you should pay attention to all of the people who did learn it, and thought it was great.

OK then: my personal preference is standard notation, not RPN.

Quote:
And, so you know, you don't have to hit it all the time on an RPN calculator. You only need to do it once, to separate the first 2 numbers you're entering, every other related calculation only makes you press the number keys and the operations. It's the non-RPN calculators that have a disadvantage here, since you actually do have to press equals a lot.

I prefer to enter the whole expression to be evaluated at once, so "equals" is pressed exactly once. I also like the TI "pretty print" feature that displays the expression in the way it would be shown in normal mathematical notation, so I can easily spot input errors without having to mentally convert back and forth between calculator notation and normal math notation.

Quote:
Quote:
and goes against standard mathematical notation.

How?

In which of the two styles is input more similar to actual mathematical notation?


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04 Dec 2010, 1:08 pm

Orwell wrote:
mcg wrote:
The HP 50 has a CAS and other powerful features, including a C compiler for its powerful ARM processor (it needs to be powerful, since most of the code is old HP 48 code running on an emulated Saturn, haha).

In what universe is a 203MHz processor underclocked to 75MHz "powerful?" TI has badly under-specced calculators as well, but calling that processor "powerful" is silly. The TI-89 Titanium with its grossly under-powered 16MHz Motorola 68k processor still outperforms the HP50 CAS for almost all common operations. And HP really has nothing to stand head-to-head against the Nspire.


Why do you think Apple underclocked the ARM11 and Cortex A8 processors in the iPhone 3G and 3GS? They were concerned about heat and battery life. The Motorola/Freescale 68K family has now gotten to the point here it is energy-efficient as it is found in other low-power applications such as industrial automation and the main CPU in a car's engine control system. Shoot, the 68K still has a home in some Cisco routers and switches.

You don't need blazing speed in a calculator IMO. To do so would be waste of batteries and CPU cycles.



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04 Dec 2010, 4:28 pm

Orwell wrote:
At the most you'd write a very short program on your calculator, and for such things it doesn't matter much what language you use. If you're writing anything serious, you need to be on a proper PC to do it.

I agree with this part, assuming that you're taking into account that you could write a large program on a computer, then transfer it to a calculator.

Quote:
My point was just that support for C isn't a meaningful selling point.

Why not?

Quote:
A good selling point for TI calculators would be the large number of applications available for it. Of course we all know the various games (Zelda, Mario, Tetris, Phoenix, etc) but it also has several chess programs, which is nice, and a number of programs for doing "real" work, such as additional math aids.

If this is a selling point, why isn't C language support a selling point? If I can program in C, then I can make games and math aids and utilities if I want, and so can anyone else.

Quote:
I prefer to enter the whole expression to be evaluated at once, so "equals" is pressed exactly once. I also like the TI "pretty print" feature that displays the expression in the way it would be shown in normal mathematical notation, so I can easily spot input errors without having to mentally convert back and forth between calculator notation and normal math notation.

The pretty print thing sounds useful, although I've never used it.

Do you end up using lots of parentheses in complicated expressions? As far as I can tell, to enter something complicated with infix notation, you'd either have to press equals a lot, or else use lots of parentheses.


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04 Dec 2010, 5:02 pm

Ancalagon wrote:
I agree with this part, assuming that you're taking into account that you could write a large program on a computer, then transfer it to a calculator.

Quote:
My point was just that support for C isn't a meaningful selling point.

Why not?

Because for little calculator things, even a crappy language like TI-Basic is good enough. If you're writing stuff on your PC and transferring it to the calculator later, then TI also has support for using C code, so no advantage there.

Quote:
Do you end up using lots of parentheses in complicated expressions? As far as I can tell, to enter something complicated with infix notation, you'd either have to press equals a lot, or else use lots of parentheses.

Define "lots." I use parentheses where appropriate, no more or less than they would be used in standard written math notation, or when using an advanced environment like Maxima or Octave on my PC.

Out of curiosity, what sort of syntax do you have to use on the HP graphing calculators (or other RPN calculators) when you want to evaluate an integral, solve a system of equations, or do complicated symbolic manipulation?


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04 Dec 2010, 11:40 pm

Orwell wrote:
Out of curiosity, what sort of syntax do you have to use on the HP graphing calculators (or other RPN calculators) when you want to evaluate an integral, solve a system of equations, or do complicated symbolic manipulation?
You can store symbolic expressions on the stack and manipulate them with RPN. They look really pretty, too. Then you can invoke various functions on them such as integration. There's also the equation writer where you can just enter the integral exactly like it appears in the textbook and store it on the stack. Then you press the eval key and you get your answer. You never ever need to end up typing alphanumeric strings on the calculator keypad, even when programming in RPL.



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05 Dec 2010, 12:11 am

mcg wrote:
Orwell wrote:
Out of curiosity, what sort of syntax do you have to use on the HP graphing calculators (or other RPN calculators) when you want to evaluate an integral, solve a system of equations, or do complicated symbolic manipulation?
You can store symbolic expressions on the stack and manipulate them with RPN. They look really pretty, too. Then you can invoke various functions on them such as integration. There's also the equation writer where you can just enter the integral exactly like it appears in the textbook and store it on the stack. Then you press the eval key and you get your answer. You never ever need to end up typing alphanumeric strings on the calculator keypad, even when programming in RPL.

Well, for example, if I wanted to evaluate a definite integral on my TI-89, I would type in something like:
∫(x^2+sin(x)),x,0,10) and then press enter. This is basically identical to the syntax in typical PC-based CAS programs.
What is the syntax for a similar function on an RPN calculator?


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