HP-12C gets 'Entry-RPN' or Error in the QSG?

[hansklav]

While preparing an RPN-Tutorial, in which I would like to indicate differences in various RPN-versions, I came across the HP-12C Quick Start Guide of 2008. On p. 7 one can read Pressing ENTER is optional after entering a number, if the next key pressed is an operation., which is (almost) the same text as in the HP 20b/30b User's Guide (p. 13).

So I presume this is an error in the HP-12C QSG, by a manual writer who is not too RPN-literate...

Does anyone of you know of a recent 12C model (the Prestige?) that has the ENTER-behaviour of the 20b/30b?
(The most recent 12C I have had in my hands is a 12C 30th Anniversary Edition, and that model definitely doesn't have 'Entry-RPN')

Thanks in advance,

Hans

[Joe Horn]

(07-04-2014 12:53 PM)hansklav Wrote:  While preparing an RPN-Tutorial, in which I would like to indicate differences in various RPN-versions, I came across the HP-12C Quick Start Guide of 2008. On p. 7 one can read Pressing ENTER is optional after entering a number, if the next key pressed is an operation., which is (almost) the same text as in the HP 20b/30b User's Guide (p. 13).

So I presume this is an error in the HP-12C QSG, by a manual writer who is not too RPN-literate...

No, it's correct, same as the HP-41 and all the older HP calculators. See the following example: you get the same result whether you include or omit the second ENTER:

2 ENTER 3 + ENTER 4 +

That's because the second ENTER follows an operation (+), as mentioned in the 12C and 20b/30b documentation.

[Thomas Klemm]

(07-04-2014 11:04 PM)Joe Horn Wrote:  2 ENTER 3 + ENTER 4 +

It's about the difference between:

2 ENTER 3 +

and

2 ENTER 3 ENTER +

With an HP-12C you get 5 and 6 while the result is 5 in both cases when using an HP-48 (or 20B/30B).

Cheers
Thomas

These are the fixed links:
HP-12C Quick Start Guide of 2008
HP 20b/30b User's Guide

[Joe Horn]

(07-05-2014 02:46 AM)Thomas Klemm Wrote:  

(07-04-2014 11:04 PM)Joe Horn Wrote:  2 ENTER 3 + ENTER 4 +

It's about the difference between:

2 ENTER 3 +

and

2 ENTER 3 ENTER +

With an HP-12C you get 5 and 6 while the result is 5 in both cases when using an HP-48 (or 20B/30B).

Hold on. You said that the following is incorrect in the 12C doc:

"Pressing ENTER is optional after entering a number, if the next key pressed is an operation." (emphasis added)

In your example, the ENTER does NOT follow an operation (as specified by HP's doc) but rather follows a numeric entry (which is NOT the situation they were talking about). In my example, it DOES follow an operation. HP's doc is correct.

You are absolutely correct that 1 ENTER 2 ENTER 3 + yields difference results in the 12C and the 20b/30b. But that's not the situation they were talking about in the above quotation from HP's doc.

[Thomas Radtke]

I read the text the same way as Hans and Thomas. To me the manual is about typing a number, pressing _optionally_ ENTER, then execute any operation, and not about ENTER following an operation. But then I'm not a native english speaker. Anyone with a german manual? :-)

[Thomas Klemm]

(07-05-2014 04:33 AM)Joe Horn Wrote:  In your example, the ENTER (...) follows a numeric entry

That's how I interpreted the following line:

Quote:Pressing ENTER is optional after entering a number

(07-05-2014 04:33 AM)Joe Horn Wrote:  You are absolutely correct that 1 ENTER 2 ENTER 3 + yields difference results in the 12C and the 20b/30b.

Where did I say so? Both results are 5.

Kind regards
Thomas

[Les Bell]

(07-05-2014 04:33 AM)Joe Horn Wrote:  In your example, the ENTER does NOT follow an operation (as specified by HP's doc) but rather follows a numeric entry (which is NOT the situation they were talking about). In my example, it DOES follow an operation. HP's doc is correct.

That's not the way I see it - the intention, rather, is that number entry into the X register can be terminated by either ENTER or an operation. In other words, what's at issue is what follows the number. The only time ENTER would follow an operation is when you want to duplicate X on the stack.

RPL machines are different because you don't enter numbers directly into the bottom level of the stack (which we RPN types think of as X) but rather into a command line, from which it will be placed into the stack by ENTER (or operated on by a function with the returned value placed on the bottom of the stack). This is just one of the many reasons I never warmed to the RPL machines. And the -30 left me distinctly cold; I converted both of mine to WP-34's after briefly experimenting.

[Joe Horn]

(07-05-2014 02:46 AM)Thomas Klemm Wrote:  It's about the difference between:

2 ENTER 3 +

and

2 ENTER 3 ENTER +

With an HP-12C you get 5 and 6 while the result is 5 in both cases when using an HP-48 (or 20B/30B).

Cheers
Thomas

(07-05-2014 06:38 AM)Thomas Klemm Wrote:  

(07-05-2014 04:33 AM)Joe Horn Wrote:  You are absolutely correct that 1 ENTER 2 ENTER 3 + yields difference results in the 12C and the 20b/30b.

Where did I say so? Both results are 5.

Kind regards
Thomas

Oops! Sorry; that was a typo. I meant to quote what you wrote, as seen above: "2 ENTER 3 ENTER +" does indeed yield difference results in the 12C (6) and 20b/30b (5).

My point remains the same: the underlined ENTER above is pressed after a number, not after an operation. Pressing ENTER after an operation is optional on all HP RPN calculators. Since this is certainly correct, and since HP's statement can be understood that way, it seems clear to me that that's what they intended it to mean. They clearly did not write it clearly.

[Joe Horn]

(07-05-2014 07:41 AM)Les Bell Wrote:  

(07-05-2014 04:33 AM)Joe Horn Wrote:  In your example, the ENTER does NOT follow an operation (as specified by HP's doc) but rather follows a numeric entry (which is NOT the situation they were talking about). In my example, it DOES follow an operation. HP's doc is correct.

That's not the way I see it - the intention, rather, is that number entry into the X register can be terminated by either ENTER or an operation. In other words, what's at issue is what follows the number.

Why do you say you disagree when we are saying exactly the same thing? To wit:

2 ENTER 3 + ENTER 4 +
The underlined ENTER is optional, because it follows an operation. This is true of EVERY HP RPN calculator, and it's exactly what HP's doc said (repeat: "Pressing ENTER is optional after entering a number, if the next key pressed is an operation.")

In other words, all they are saying is this:

In "Operation [ENTER] Number", the ENTER is optional.

... and that's correct for every HP RPN calculator.

Quote:The only time ENTER would follow an operation is when you want to duplicate X on the stack.

Not true. That's the only time that you MUST press ENTER, but it's not the only time it's allowed. It's optional (albeit unnecessary), as seen above... and that's all that HP was saying.

[Thomas Klemm]

(07-05-2014 09:26 PM)Joe Horn Wrote:  My point remains the same: the underlined ENTER above is pressed after a number, not after an operation. Pressing ENTER after an operation is optional on all HP RPN calculators. Since this is certainly correct, and since HP's statement can be understood that way, it seems clear to me that that's what they intended it to mean. They clearly did not write it clearly.

Maybe the context is missing. Thus I'm adding the previous sentence:

Quote:Reverse Polish Notation (RPN) Mode
(...)
In RPN mode, numbers are entered first, separated by pressing [ENTER], followed by an operation key. Pressing [ENTER] is optional after entering a number, if the next key pressed is an operation.

This is from the HP-12C Owner's Handbook:

Quote:Simple Arithmetic Calculations
(...)
Pressing [ENTER] tells the calculator that you have completed entering the number: it terminates digit entry. You need not press [ENTER] after keying in the second number because the [+], [−], [×], and [÷] keys also terminate digit entry.

Thus it's already wrong in the original. It's not optional to press the [ENTER] key: it's wrong to do it in this case.

Let me write your example in two lines:
2 ENTER 3 +
ENTER 4 +

This case is handled in the next section:

Quote:Chain Calculations
Whenever an answer has just been calculated and is therefore in the display, you can perform another operation with this number by simply keying in the second number and then pressing the
operation key: you need not press [ENTER] to separate the second number from the first. This is because when a number is keyed in after a function key (such as [+], [−], [×], [÷], etc.) is pressed, the result of that prior calculation is stored inside the calculator − just as when the [ENTER] key is pressed.

While that ENTER is optional in the case of the HP-12C it is not true for the HP-48 when calculating 6×(2 + 3 + 4):
6 ENTER
2 ENTER 3 +
ENTER 4 +
×

You either get 45 or 54.

I still have difficulties to follow how you end up with:

Quote:In "Operation [ENTER] Number", the ENTER is optional.

Wouldn't that rather be:
Pressing [ENTER] is optional before entering a number, if the previous key pressed is an operation.

Cheers
Thomas

[Les Bell]

(07-05-2014 09:44 PM)Joe Horn Wrote:  Why do you say you disagree when we are saying exactly the same thing? To wit:

I think we're in a tangle because the whole thing is so badly written, and fails to provide any explanation of why you'd want to press ENTER in the first place. You see, for anyone who knows what ENTER does, it would never occur to them to press ENTER between an operation and a number in the first place - so it's an explanation of an unnatural act.

An ENTER in that position is only "optional" in the sense that it disables automatic stack lift, so that after copying X into Y, the contents of X are over-written by the entered number. But if you just go ahead and start to enter the number anyway, the automatic stack lift preserves everything, with the previous X now in Y and the new number in X.

So, the original HP text - "Pressing ENTER is optional after entering a number, if the next key pressed is an operation." - is unclear and emphasises the wrong concept: the next thing to happen. The focus should be on what's happening now - number entry - and how you tell the calculator the number is ended. I would have written, "When entering a number into the calculator, you can end the number by pressing ENTER - especially to separate it from the next number - or just press an operation".

I suspect the automatic disabling of stack lift is only there to simplify life for those who get a bit over-enthusiastic with ENTER; experienced RPN users probably rarely trigger it.

[Les Bell]

(07-05-2014 09:44 PM)Joe Horn Wrote:  In other words, all they are saying is this:

In "Operation [ENTER] Number", the ENTER is optional.

... and that's correct for every HP RPN calculator.

Hang on - I see the confusion. That's not what's at issue; what I'm writing about is

"Number [ENTER] Operation"

in response to the original quote: "Pressing ENTER is optional after entering a number, if the next key pressed is an operation." This reinforces my point that the original places the emphasis on the wrong concept.

I might press "operation ENTER ENTER Number", if I want to duplicate X before entering another number, but I'd never press "Operation ENTER Number" or "Number ENTER Operation".

[Joe Horn]

(07-06-2014 01:01 AM)Les Bell Wrote:  I think we're in a tangle because the whole thing is so badly written...

We definitely agree on that!

(07-06-2014 01:09 AM)Les Bell Wrote:  Hang on - I see the confusion. That's not what's at issue; what I'm writing about is

"Number [ENTER] Operation"

in response to the original quote: "Pressing ENTER is optional after entering a number, if the next key pressed is an operation." ...

In my famously humble opinion, that's not what the sentence by HP means at all. "The next key pressed" is syntactically after "after entering a number" and therefore means "if the next key pressed after entering a number is an operation". An example of that is:

Number Operation ENTER Number

And as we all know, that ENTER is optional. Wow, HP's explanation really is worded poorly. A gold star goes to the person who words it most clearly. Here's my first attempt:

"Separating numeric entries can be done either by pressing ENTER or by performing an operation, e.g. 2 ENTER 3 + performs 2+3, and 2 √ 3 + performs √2+3."

Too wordy. Please simplify... but not too much, as per Einstein's dictum, lest ambiguity reappear.

[kakima]

Quote:I might press "operation ENTER ENTER Number", if I want to duplicate X before entering another number, but I'd never press "Operation ENTER Number" or "Number ENTER Operation".

Just out of curiosity, how would you calculate 3.7 + 3.7^2 in RPN? I'd press 3 . 7 ENTER x^2 followed by + .

[Les Bell]

(07-06-2014 02:42 AM)kakima Wrote:  Just out of curiosity, how would you calculate 3.7 + 3.7^2 in RPN? I'd press 3 . 7 ENTER x^2 followed by + .

lol! I should never say never, should I? Yes, that's exactly how I would do it. And I wouldn't think twice about it, it's so automatic. But of course, in this example, the ENTER isn't optional.

[Les Bell]

(07-06-2014 02:08 AM)Joe Horn Wrote:  In my famously humble opinion, that's not what the sentence by HP means at all. "The next key pressed" is syntactically after "after entering a number" and therefore means "if the next key pressed after entering a number is an operation".

Are you saying that "entering a number" means "[sequence of digits] ENTER"? Because I think it's just "[sequence of digits]" (I'm ignoring EEX and ., here). In which case, "if the next key pressed after entering a number is an operation", then you didn't press ENTER - because you didn't consider it an option. And as kakima just ably demonstrated, if you did press ENTER, it was for good reason, and it wasn't optional.

For the novice, the confusion probably arises because of the overloading of the ENTER key; it's sometimes used to terminate number entry, and sometimes to duplicate X into Y, and sometimes both. And the distinction requires the introduction of the notion of automatic stack lift, and its disabling by certain operations.

Quote:"Separating numeric entries can be done either by pressing ENTER or by performing an operation, e.g. 2 ENTER 3 + performs 2+3, and 2 √ 3 + performs √2+3."

I'd avoid that word "entries" - too confusing! Rather "Separating two numbers can be done ...". Or I'd approach the question by viewing it from the calculator's point of view: "How does the calculator know when you've finished entering a number? You can either press an operator key, or, if you want to immediately enter the next number, press ENTER to separate them" (or even "press ENTER to copy the first number into the Y register and allow the next number to overwrite X". Yeah, it's wordy, but clarity trumps word count, for the reader. Otherwise, we wouldn't be here.

[hansklav]

Wow, my post (and especially my remark that the HP-12C Quick Start Guide of 2008 might contain an error) provoked quite some discussion!

My original question was if anyone of you knows of a recent 12C model (the Prestige?) that has the ENTER-behaviour of the 20b/30b?

What I meant was: is there any recent 12C model (after 2008) that has the following behaviour:
2 ENTER 3 ENTER + (Answer: 5; here the second ENTER is optional)
Because that is the behaviour of the 20b and 30b. And of course that is the way all RPL calculators respond, but for a 4-level stack calculator this is quite unusual, because all other classical 4-level stack RPN calculators would give the answer 6 when you key in 2 ENTER 3 ENTER +

The text I quoted from the HP-12C QSG was (now including the preceding sentence): In RPN mode, numbers are entered first, separated by pressing ENTER, followed by an operation key. Pressing ENTER is optional after entering a number, if the next key pressed is an operation. Because this is the same text I read in the 20b and 20b/30b manuals (apart from the fact that there the ENTER-key is renamed 'INPUT') it led me to believe that HP might have changed the firmware of its recent 12C models to have this new and unusual (but for newbies more natural) behaviour. It would mean a revolution for the 12C world, so I did'nt expect it to be true, but I thought: maybe HP just did it, so let's ask the forum.

Now that none of you seem to know such a revolutionary 12C model (at least nobody mentioned any), for the time being I will presume that none exists, so I will not mention the recent 12C models alongside the 20b and 30b as having 'Entry RPN' in my forthcoming RPN Tutorial.

'Entry RPN' is how Richard J. Nelson calls this RPN version (which includes all RPL calculators and the 20b and 30b) in his article 'How RPN Evolves'.

Joe Horn's respons indicated an ambiguity in the above mentioned sentence, and indeed he is right that this sentence can be understood as meaning another use of the ENTER key. Still I am convinced that the use of that sentence (obviously copied from the HP 20b Business Consultant Financial Calculator Manual) in the HP 12c Financial Calculator Quick Start Guide is probably an error, unless there would actually exist a HP-12C with Entry RPN . The main reason for my conviction is that the totally superfluous and puzzling (imho) use of ENTER after an operator (and not a number) and followed by another number is only mentioned in the original HP-35 Operating Manual (in the appendix "An Algorithm") and in the HP-45 Owner's Handbook (in Appendix A. Stack Algorithm and Flow Chart). In all later Manuals that I am aware of it is not mentioned anymore. It would be highly improbable that this, again: optional but totally superfluous, use of ENTER should be mentioned in a Quick Start Guide for the HP-12C.

And thinking about this and reading Richard Nelsons article and the original HP-35 and 45 Manuals it occurred to me that the word ENTER itself as name for the key we are all so fond of is ambiguous too.

But that will be the subject of another post. Stay tuned ;-)

Hans

[RMollov]

(07-06-2014 02:42 AM)kakima Wrote:  Just out of curiosity, how would you calculate 3.7 + 3.7^2 in RPN? I'd press 3 . 7 ENTER x^2 followed by + .

I'd do:
3.7 ENTER ENTER * +
(shortest finger travel)


On the OP issue : regardless of the poor wording, one quickly figures out the ENTER behavior;
I've seen (lots of) not-needed ENTERs only in novice's programs.

[CosmicTruth]

(07-06-2014 02:42 AM)kakima Wrote:  

Quote:I might press "operation ENTER ENTER Number", if I want to duplicate X before entering another number, but I'd never press "Operation ENTER Number" or "Number ENTER Operation".

Just out of curiosity, how would you calculate 3.7 + 3.7^2 in RPN? I'd press 3 . 7 ENTER x^2 followed by + .

this gets "too fue arguments" error

(07-06-2014 12:44 PM)RMollov Wrote:  

(07-06-2014 02:42 AM)kakima Wrote:  Just out of curiosity, how would you calculate 3.7 + 3.7^2 in RPN? I'd press 3 . 7 ENTER x^2 followed by + .

I'd do:
3.7 ENTER ENTER * +
(shortest finger travel)


On the OP issue : regardless of the poor wording, one quickly figures out the ENTER behavior;
I've seen (lots of) not-needed ENTERs only in novice's programs.

this gets "too fue arguments" error also
now back to our normally scheduled argument...

Pressing [enter] is optional after entering a number, if the next key
pressed is an operation.

NOTE: pressing [Input] or [=] is optional after keying in a number, if the next key
pressed is an operation.

[RMollov]

(07-06-2014 01:31 PM)CosmicTruth Wrote:  this gets "too fue arguments" error

No it doesn't, we're talking RPN here.