RPN vs The Big Three

[Matt Agajanian]

Hi all.

Even as a happy owner of several recent Sharp, Casio, and TI calcs, it seems to me RPN is still the superior entry system.

First, even if the input method is linear, the burden of keeping track of parentheses is still an issue. Second, while stating the expression in VPAM (Casio), Write View (Sharp), or MathPrint (TI), you’re adding keystrokes by moving the cursor in any of four directions to place operators in the right positions of the equation. I know this sounds like I’m putting HP’s Equation Writer straight in the bull’s eye to shoot it down, that’s not my intention.

On the other hand, with RPN, the only keystrokes you need are the ones to calculate your expression

[pascal_meheut]

I think so too and this is the only entry method I use today but when I was a student, I remember liking my Casio 702p because I could see the entire formula before evaluating it.
It was a bit slower but easier and safer and even more if you used memories, i.e. named variables with the Casio (or the Sharps).

[halbitton]

On the 50G, you can build an un-evaluated equation right on the stack using RPN keystrokes, with the following caveat... you have to start the equation by entering the innermost term as an algebraic object (put it between apostrophes using algebraic keystrokes). The calculator will not evaluate the algebraic, nor will it evaluate subsequent operations that you put on (using RPN keystrokes). Rather, it will magically build your equation right before your eyes, putting in brackets, etc as appropriate. When done, you can hit EVAL to crunch. I think this works on any RPL machine, as well.
Best regards, Hal

[Steve Simpkin]

(11-17-2022 08:58 PM)halbitton Wrote:  On the 50G, you can build an un-evaluated equation right on the stack using RPN keystrokes, with the following caveat... you have to start the equation by entering the innermost term as an algebraic object (put it between apostrophes using algebraic keystrokes). The calculator will not evaluate the algebraic, nor will it evaluate subsequent operations that you put on (using RPN keystrokes). Rather, it will magically build your equation right before your eyes, putting in brackets, etc as appropriate. When done, you can hit EVAL to crunch. I think this works on any RPL machine, as well.
Best regards, Hal

This sounds cool but I can’t seem to reproduce it. Can you list the keys used for a simple example? Thanks.

[Thomas Klemm]

(11-18-2022 05:19 AM)Steve Simpkin Wrote:  Can you list the keys used for a simple example?

It also works with the HP-48G.
Assuming nothing is assigned to variable X:

1 X+

1: '1+X'

1 X-

2: '1+X'
1: '1-X'

/

1: '(1+X)/(1-X)'

With numbers the terms have to be entered algebraically to prevent evaluation:

'1+3' ENTER

1: '1+3'

'1-3' ENTER

2: '1+3'
1: '1-3'

/

1: '(1+3)/(1-3)'

EVAL

1: -2

[Steve Simpkin]

Thank you Thomas for the examples. That works on the HP-48SX and HP-28S as well.

[Matt Agajanian]

(11-18-2022 06:35 AM)Thomas Klemm Wrote:  

(11-18-2022 05:19 AM)Steve Simpkin Wrote:  Can you list the keys used for a simple example?

It also works with the HP-48G.
Assuming nothing is assigned to variable X:

1 X+

1: '1+X'

1 X-

2: '1+X'
1: '1-X'

/

1: '(1+X)/(1-X)'

With numbers the terms have to be entered algebraically to prevent evaluation:

'1+3' ENTER

1: '1+3'

'1-3' ENTER

2: '1+3'
1: '1-3'

/

1: '(1+3)/(1-3)'

EVAL

1: -2

Now, that’s cool!

I think my excitement will hold over till my new calc arrives today!

Nah! This will hold me over for a few days at least.

Thanks

[toml_12953]

(11-17-2022 04:04 AM)Matt Agajanian Wrote:  Hi all.

Even as a happy owner of several recent Sharp, Casio, and TI calcs, it seems to me RPN is still the superior entry system.

First, even if the input method is linear, the burden of keeping track of parentheses is still an issue. Second, while stating the expression in VPAM (Casio), Write View (Sharp), or MathPrint (TI), you’re adding keystrokes by moving the cursor in any of four directions to place operators in the right positions of the equation. I know this sounds like I’m putting HP’s Equation Writer straight in the bull’s eye to shoot it down, that’s not my intention.

On the other hand, with RPN, the only keystrokes you need are the ones to calculate your expression

The difference is that you enter expressions in an algebraic system the way you'd write them. You enter them into RPN the way you'd solve them.

[Matt Agajanian]

(11-18-2022 09:06 PM)toml_12953 Wrote:  

(11-17-2022 04:04 AM)Matt Agajanian Wrote:  Hi all.

Even as a happy owner of several recent Sharp, Casio, and TI calcs, it seems to me RPN is still the superior entry system.

First, even if the input method is linear, the burden of keeping track of parentheses is still an issue. Second, while stating the expression in VPAM (Casio), Write View (Sharp), or MathPrint (TI), you’re adding keystrokes by moving the cursor in any of four directions to place operators in the right positions of the equation. I know this sounds like I’m putting HP’s Equation Writer straight in the bull’s eye to shoot it down, that’s not my intention.

On the other hand, with RPN, the only keystrokes you need are the ones to calculate your expression

The difference is that you enter expressions in an algebraic system the way you'd write them. You enter them into RPN the way you'd solve them.

EXACTLY!

[Garth Wilson]

(11-18-2022 09:06 PM)toml_12953 Wrote:  The difference is that you enter expressions in an algebraic system the way you'd write them. You enter them into RPN the way you'd solve them.

I got another engineer into RPN when I told him, "Algebraic tells you what you get. RPN tells you how you get there." See also my post at https://hpmuseum.org/forum/thread-19093-...#pid166016 . Someone emailed me and asked if they could quote me in a book they were writing.