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Probaby gonna get a ton of flak for this but...
04-14-2020, 03:40 AM (This post was last modified: 04-14-2020 03:42 AM by Solver.)
Post: #1
Probaby gonna get a ton of flak for this but...
Why do so many here want full RPL support for the HP Prime? I looked at how RPL is done and compared it to the Textbook entry method and I'm gonna be honest. It looks like the same amount of steps, more or less. I don't really see what's so desirable about it.

Perhaps I could understand back in the old days when calculators did not have the option of having a touchscreen. It probably was a lot faster indeed to use RPL. But now? Eh...
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04-14-2020, 04:55 AM
Post: #2
RE: Probaby gonna get a ton of flak for this but...
Did you mean to say RPN? But yeah, I couldn't care less about it, no use for me as an engineer.
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04-14-2020, 10:36 AM
Post: #3
RE: Probaby gonna get a ton of flak for this but...
(04-14-2020 04:55 AM)Dands Wrote:  Did you mean to say RPN? But yeah, I couldn't care less about it, no use for me as an engineer.

He could have meant RPL, the programming language using RPN. It uses « and » to modularize programs.

Code:
« 
    0       @ Start with zero on the stack
    1 10    @ Loop from 1 to 10
    FOR I   @ "I" is the local variable
       I +  @ Add "I" to the running total
    NEXT    @ Repeat...
 »

Tom L
Cui bono?
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04-14-2020, 04:41 PM
Post: #4
RE: Probaby gonna get a ton of flak for this but...
It is true that modern textbook entry systems are competitive with RPN on a keystroke basis. RPN has the advantage that the result of the last calculation is on the stack ready for the next calculation. The "Ans" key functionality of the Prime, etc. largely makes up for this advantage but not always.

Partly it's just a matter of what one is used to. I have been using HP RPN calculators for 40 years so RPN is what I'm used to. If one grew up using TI calculators RPN would similarly seem foreign to them.

I use the HP 50g a lot more often than the Prime, but RPN is not the only reason. The CAS/Home split personality, lack of a debugger in CAS, and rather long-winded procedural programming language are other stumbling blocks for me. There are many aspects of the Prime that I really like- speed and memory of course, more powerful CAS, record of the last 100 operations, etc.

For quick'n'dirty interactive problem solving though, I will always reach for the 50g.
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04-14-2020, 07:38 PM
Post: #5
RE: Probaby gonna get a ton of flak for this but...
I have had experience with the most powerful RPN calculator hp-50g. #× # ×#×1 "space" #×#×#×2 "+" ... #×#×#×n ... EXE ... .How can I return #×1 or #×2 ... or #×n or "non evals" on the stack? while everything happens in "exact mode [off]" after [ENTER]. There was a terrible disease - "RPN" of the brain.
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04-14-2020, 08:15 PM
Post: #6
RE: Probaby gonna get a ton of flak for this but...
As John Keith mentioned. It is more of a personal preference to use RPN/RPL over algebraic/textbook entry. For many decades almost all HP calculators were RPN entry only so HP users became accustomed to and trusted using RPN to solve problems. At the beginning of handheld scientific calculators, there were were many clear advantages to using RPN over so-called algebraic entry. RPN very closely mimicked how you would solve problems using a pencil and paper (or slide rule) so it was somewhat easier for engineers and scientists to transition to using it. Most importantly it allowed you to work with arbitrary complex equations that could not easily be solved using algebraic calculators of the time. Remember TI's first real scientific calculator, the TI-50, didn't even have parenthesis keys let alone know about more then the most basic rules of operator precedence. There were many complex problems it could not solve without carefully determining the best way (order) to enter the problem, writing down intermediate answers and then manually typing them back in. Over the years there were many, many variations on algebraic entry calculators so you had to intimately know the "rules" of entering a problem on your specific model to get a correct answer on a complex equation. Even today with advanced textbook entry, entering a problem like 48/2(9+3) will get you different answers from different calculator models. RPN on the other hand has been very consistent over the decades, with only minor differences when RPL appeared in the late 1980's.

Over time, with the advancements in technology, the advantages of RPN are less important than they used to be but for those of us who grew up using HP calculators, most of us still prefer to use RPN/RPL entry. It is particularly good at solving quick exploratory problems where seeing the intermediate results is still important.

In conclusion, I'll leave you with this tidbit of knowledge to considerSmile
Enter vs Equals
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04-14-2020, 09:13 PM
Post: #7
RE: Probaby gonna get a ton of flak for this but...
(04-14-2020 08:15 PM)Steve Simpkin Wrote:  ... entering a problem like 48/2(9+3) will get you different answers from different calculator models....

The order of operations, and the rules of precedence don't change (PEMDAS). If you're getting different answers from different calculator models, the "different answers" are likely to be only reflections from your own inputs.
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04-14-2020, 10:12 PM
Post: #8
RE: Probaby gonna get a ton of flak for this but...
(04-14-2020 09:13 PM)DrD Wrote:  
(04-14-2020 08:15 PM)Steve Simpkin Wrote:  ... entering a problem like 48/2(9+3) will get you different answers from different calculator models....

The order of operations, and the rules of precedence don't change (PEMDAS). If you're getting different answers from different calculator models, the "different answers" are likely to be only reflections from your own inputs.

In this case, the order of operations for implied multiplication is not universal. This is an example of a poorly written equation. For another example see:
https://www.hpmuseum.org/forum/thread-11...#pid108526
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04-15-2020, 12:11 AM
Post: #9
RE: Probaby gonna get a ton of flak for this but...
(04-14-2020 09:13 PM)DrD Wrote:  
(04-14-2020 08:15 PM)Steve Simpkin Wrote:  ... entering a problem like 48/2(9+3) will get you different answers from different calculator models....

The order of operations, and the rules of precedence don't change (PEMDAS). If you're getting different answers from different calculator models, the "different answers" are likely to be only reflections from your own inputs.


Those calculators did NOT follow the rules!
- -
VPN
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04-15-2020, 01:35 AM (This post was last modified: 04-15-2020 01:36 AM by Steve Simpkin.)
Post: #10
RE: Probaby gonna get a ton of flak for this but...
(04-15-2020 12:11 AM)CyberAngel Wrote:  
(04-14-2020 09:13 PM)DrD Wrote:  The order of operations, and the rules of precedence don't change (PEMDAS). If you're getting different answers from different calculator models, the "different answers" are likely to be only reflections from your own inputs.


Those calculators did NOT follow the rules!
- -
VPN

There is no universally accepted "rule" for that equation as it is written. About 50% of people asked "What is the answer to 48/2(9+3)" will respond with "2" and the other 50% will answer "288". The lesson here is don't write equations like that.

Here is a list of calculators that accept implied multiplication and the answers they returned.

Answer = 288
--------------------------
HP-50G
HP 35s
HP Prime (Algebraic entry)
TI-73
TI-83
TI-84
TI-86
TI-89
TI-92
TI-34 MultiView
Google
WolframAlpha

Answer = 2
--------------------------
HP Prime (Textbook entry)
Casio fx-115ES Plus
Casio fx-CG50
Casio fx-9860G AU
Casio fox-300MS Plus
TI-80
TI-81
TI-82
TI-85
Sharp EL-W535X

https://www.physicsforums.com/threads/48...on.488334/
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04-15-2020, 01:40 AM
Post: #11
RE: Probaby gonna get a ton of flak for this but...
(04-14-2020 09:13 PM)DrD Wrote:  
(04-14-2020 08:15 PM)Steve Simpkin Wrote:  ... entering a problem like 48/2(9+3) will get you different answers from different calculator models....

The order of operations, and the rules of precedence don't change (PEMDAS). If you're getting different answers from different calculator models, the "different answers" are likely to be only reflections from your own inputs.

Emphasis mine,

So, only my input affects all those calculators - not their different implementations?
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VPN
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04-15-2020, 02:54 AM (This post was last modified: 04-15-2020 02:55 AM by toml_12953.)
Post: #12
RE: Probaby gonna get a ton of flak for this but...
(04-15-2020 01:35 AM)Steve Simpkin Wrote:  There is no universally accepted "rule" for that equation as it is written. About 50% of people asked "What is the answer to 48/2(9+3)" will respond with "2" and the other 50% will answer "288". The lesson here is don't write equations like that.

Just because 50% give the wrong answer (2) doesn't mean there are no rules. It just means that 50% don't know the rules.

With the Prime in textbook mode, the user has to know the expression in parentheses doesn't go in the denominator when obeying the standard rules. If you type without thinking, Prime gives

48
--------
2(9+3)

which is wrong. Not because the calculator is wrong but the user is wrong for not moving the cursor out from under the denominator before pressing Enter like so:

48
--- (9+3)
2

A clear case of GIGO (Garbage In, Garbage Out)

Another example is even simpler: 2/5+7

Without thinking:

2
-----
5+7

Proper:

2
--- + 7
5

The calculator has no way of knowing when the denominator should end. It's up to the user to manually move the cursor to the right.

Tom L
Cui bono?
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04-15-2020, 04:54 AM
Post: #13
RE: Probaby gonna get a ton of flak for this but...
(04-15-2020 02:54 AM)toml_12953 Wrote:  
(04-15-2020 01:35 AM)Steve Simpkin Wrote:  There is no universally accepted "rule" for that equation as it is written. About 50% of people asked "What is the answer to 48/2(9+3)" will respond with "2" and the other 50% will answer "288". The lesson here is don't write equations like that.

Just because 50% give the wrong answer (2) doesn't mean there are no rules. It just means that 50% don't know the rules.

With the Prime in textbook mode, the user has to know the expression in parentheses doesn't go in the denominator when obeying the standard rules. If you type without thinking, Prime gives

48
--------
2(9+3)

which is wrong. Not because the calculator is wrong but the user is wrong for not moving the cursor out from under the denominator before pressing Enter like so:

48
--- (9+3)
2

A clear case of GIGO (Garbage In, Garbage Out)
Another example is even simpler: 2/5+7
Without thinking:

2
-----
5+7

Proper:

2
--- + 7
5

The calculator has no way of knowing when the denominator should end. It's up to the user to manually move the cursor to the right.

True, for the case of the Prime in Textbook mode, you have a choice how you enter the equation. For most of the other models shown above, you enter "48/2(9+3)" exactly as shown and the calculator logic determines the order of operations.

[Image: headasplode-jpg.34146]

The point was that with an algebraic entry calculator you are responsible for knowing how your model will interpret a given equation. They do not all use the same rules.
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04-15-2020, 09:26 AM
Post: #14
RE: Probaby gonna get a ton of flak for this but...
(04-15-2020 04:54 AM)Steve Simpkin Wrote:  The point was that with an algebraic entry calculator you are responsible for knowing how your model will interpret a given equation. They do not all use the same rules.

True. IMHO, implied multiplication should be treated the same as an explicit multiplication sign. When you do enter the expression on the fx-CG50 at least it shows you where it inserted parentheses around the implied multiplication to give the answer 2.

When you enter
48÷2(9+3)
it transforms it into
48÷(2(9+3))

Tom L
Cui bono?
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04-18-2020, 11:16 AM (This post was last modified: 04-18-2020 11:22 AM by Solver.)
Post: #15
RE: Probaby gonna get a ton of flak for this but...
Whoops! Sorry, forgot I made this thread. lol Yes though, I meant RPN mostly. Thank you everyone for your answers!

For the record, I rather love Textbook entry. Anyone can read it and it's easy to use. Although, as people said, you obviously have to know the difference between 48/2(9+3) and (48/2)*(9+3), but I think we're all big boys and girls here and know the difference. And if you don't know the difference, then you probably shouldn't be using the HP Prime.

I will definitely assent that RPN has the advantage of giving you answers midway through a problem, should that be something you need, but I would argue, at least with the HP Prime and similar calculators, that if you really need the answers midway through a problem, you can and probably should just do it piecemeal. And with HP Prime's double-tap-to-copy-to-entry-field functionality, it's even super fast.
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