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The early history of HP calculators

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Re: The early history of HP calculators

#71

Post by dm319 »

waynecochran wrote: post #29

When I started college in 1985, every Physics student had an HP41C. You were at a distinct disadvantage on an exam if you had an infix calculator. I still have my HP41CX that my dad bought me in 1985. Now I don't see any of the students using them. What happened? When I used to teach, I would write a large expression on the board and challenge students to a calculator duel -- me using my 1985 HP41CX and them using th…

>What happened?

I don't get it either. Even if HP lost interest, why didn't anyone continue with RPN (patents, maybe?).

I think RPN is both better for learning at school (you see intermediates, and you learn operator order), as well as general use. I love that you can just get stuck in calculating without having to worry about getting it all in the right order at first.

I'd love my children to use RPN when they reach that age, but there is a lack of RPN calculators on the market, a lack of knowledge at school and it may even be banned by the time they need to take an exam.

Re: The early history of HP calculators

#72

Post by tremendo »

carussell wrote: post #58
tremendo wrote: post #49

Earlier quoted context omitted.

LOL why bother with a calculator? 16 ÷ 8 easy! I always think of RPN as somewhat akin to using VIM (editor), once you learn it, it becomes unconscious, automatic. I for one don't see how the RPN form relies "on a more extensive cook".

Looks like you skipped over this part of my comment in your attempt to be condescending: > At least, it's how I would have entered it if the figures weren't so small.

I have to apologize. What actually came to mind was that I know some probably couldn't make the mental leap to again divide by the other factor when they see the multiplication symbol there as written, then reaching for the calculator. I totally see now how it appears I was attempting to be condescending, sorry.

Re: The early history of HP calculators

#73

Post by joezydeco »

waynecochran wrote: post #29

When I started college in 1985, every Physics student had an HP41C. You were at a distinct disadvantage on an exam if you had an infix calculator. I still have my HP41CX that my dad bought me in 1985. Now I don't see any of the students using them. What happened? When I used to teach, I would write a large expression on the board and challenge students to a calculator duel -- me using my 1985 HP41CX and them using th…

What happened is every high school mandating the use of the TI-35 and their brethren, making sure those kids are so used to working with infix calculators that they never approach an RPN.

Re: The early history of HP calculators

#74

Post by antod »

dm319 wrote: post #68
ScottBurson wrote: post #64

Earlier quoted context omitted.

I don't think that's fair. Either form requires some mental stack space to convert to the other form. It's just that people are more used to reading and writing infix.

Yes, I find complex equations to be far easier to calculate in RPN. Even if you get stuck you have a useful intermediate. On algebraic I find I'm having to back pedal to sort out parentheses for lower order operators.

Agreed. Although getting a multiline display like the 42S or (gasp) 48S helped a lot with keeping track of the stack.

edit: 42S not 42C

Re: The early history of HP calculators

#75

Post by copperx »

na85 wrote: post #42
dm319 wrote: post #16

Getting good condition HP calculators can be quite expensive second hand. People interested in buying a new one should check out swissmicros [1]. They are bringing out an HP42s clone with quad precision decimal accuracy, which I'm looking forward to! [2] [1] http://www.swissmicros.com/ [2] https://www.youtube.com/watch?v=8LatjXPgLI8 EDIT: I don't have any involvement with swissmicros apart from anticipating their new…

I bought an HP50g, new, just a few years ago after my 48 died. I believe that they have a new one called the Prime that's still in production. My 50g is an excellent machine.

My trusty HP50g which I used in my undergrad was stolen, and it still makes me mad because it's unlikely that whoever took it will take full advantage of it.

Re: The early history of HP calculators

#76

Post by carussell »

jaclaz wrote: post #59
carussell wrote: post #38

Earlier quoted context omitted.

[1 3 Enter 3 + 4 Enter 2 × ÷] is 10 button presses for RPN. [1 3 + 3 = ÷ 4 ÷ 2 =] is also 10 button presses, and how I would have entered it on an infix $10 TI-30XA during an exam. (At least, it's how I would have entered it if the figures weren't so small.) You could argue that it's cheating to "cook" the input beforehand so that the '4×2' divisor becomes two '4' and '2' divisors, but then you would have to ignore t…

Yes, you replaced (correctly) a x with a /, and this does require some (little) effort. There is no "cooking" in the RPN input, the way you input is a little more similar to how you do manually operations, and in the order numbers are written from left to right, but of course beauty is only in the eye of the beholder. A (as well small) advantage is that on RPN you "see" that you are dividing 16 by 8, particularly - a…

> There is no "cooking" in the RPN input, the way you input is a little more similar to how you do manually operations

You do your pen and paper algebra in RPN?

The point of my "cooked" input comment wasn't to say that the mental overhead to convert to RPN is complicated or cannot come naturally after some time getting used to it; it was a defense of my swapping the division operation to multiply by the reciprocal. The idea is that if I hadn't pre-emptively addressed this in my first comment, I expected for someone to claim that I was cheating and feeding in "cooked" input for the infix case. My point is that if you recognize that converting to RPN is trivial and want to count that as a zero-cost operation when scoring the efficiency of RPN, then you have to recognize that converting the divisor to a reciprocal factor is just as trivial (moreso, really) and should be scored as a zero-cost operation, too.

Otherwise, what you have is an inconsistent standard where the infix conversion gets arbitrarily counted against the infix case, but the RPN conversion is somehow "free".

> Now be nice, and do (13+3)/(3x(SQR(4+2)))

I got 15 button presses, compared to your 14. I can live with that, given this is a calculator that can be picked up for $10. And that's the biggest savings, considering that the other things I had to worry about as a student were being gouged by mandatory meal plans and expensive, low-quality, on-campus housing.

FWIW, I actually like postfix notation.[1]

1. https://news.ycombinator.com/item?id=2213066

Re: The early history of HP calculators

#77

Post by hota_mazi »

ScottBurson wrote: post #64
hota_mazi wrote: post #54

Earlier quoted context omitted.

> The magic is the automatic saving of subexpressions on a stack. Once you got the hang of it, you would never want to go back to an infix calculator I was one of these smug HP calculator owners back in high school and college. I loved it and spent hours hacking on it (and also secretly enjoyed the fact that nobody borrowed it since hardly anyone knew how to use it). Years later, I started realizing that the reason w…

I don't think that's fair. Either form requires some mental stack space to convert to the other form. It's just that people are more used to reading and writing infix.

For regular notation, you just type all the characters as you read them, including parentheses. This requires less mental activity on the person, as opposed to RPN, which forces you to first parse the entire expression and identify the most nested expression and process outward from that point on.

Re: The early history of HP calculators

#78

Post by grzm »

hota_mazi wrote: post #77
ScottBurson wrote: post #64

Earlier quoted context omitted.

I don't think that's fair. Either form requires some mental stack space to convert to the other form. It's just that people are more used to reading and writing infix.

For regular notation, you just type all the characters as you read them, including parentheses. This requires less mental activity on the person, as opposed to RPN, which forces you to first parse the entire expression and identify the most nested expression and process outward from that point on.

Anecdote, but I was surprised to find that my father (who used his HP with RPN extensively) found "normal" calculators more difficult to use. At the end of the day I think it comes down to what you're used to. Requiring more or less mental activity can come down to how closely the activity matches what one is comfortable with.

Re: The early history of HP calculators

#79

Post by zokier »

dm319 wrote: post #67
zokier wrote: post #28

Earlier quoted context omitted.

One thing that has always befuddled me with HP calcs is their model numbers that don't seem to follow any rhyme or reason. How does the functionality of DM42 compare to for example WP34? And how does -48 compare, besides the relatively useless graphing capability? I see lots of people also preferring some other models (15, 16, 35, 41 etc), which I would have imagined to be strict subsets of these "juggernauts", but m…

The 48 was quite a bit bigger than the 42s, which I think is the main downside. A bit of googling suggests the 48 contains similar features to the 42s, and probably more. It can also show the full 4 level stack - the 42s showed 2. However, you're looking for the best all-round scientific calculator (form factor restricted!) the 42s probably wins. The voyager series (including the 15 and 16) were well-made and in land…

How's the menu interface in HP calcs, is it strictly better than non-menu ones, or is it more of a usability compromise to allow packing more features? In other words, are the non-menu ones better for the subset of features they have?

Re: The early history of HP calculators

#80

Post by xelxebar »

hota_mazi wrote: post #77
ScottBurson wrote: post #64

Earlier quoted context omitted.

I don't think that's fair. Either form requires some mental stack space to convert to the other form. It's just that people are more used to reading and writing infix.

For regular notation, you just type all the characters as you read them, including parentheses. This requires less mental activity on the person, as opposed to RPN, which forces you to first parse the entire expression and identify the most nested expression and process outward from that point on.

I'm not sure about the 41C, but I have a 32SII and you don't need to process "from the inside out".

When you encounter an open parenthesis, then you just push the following number onto the stack, when you encounter a close parenthesis, you just perform the relevant arithmetic operation.

For the example

    2 * (3 + 4)
we can do this

    Input            Stack
    2                   2
    3                   3,2
    4                   4,3,2
    +                   7,2
    *                   14
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