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Dushan
23rd Mar 2008, 16:55
How many of you use a calculator that has Reverse Polish Notation? As far as I know only HP makes them. I use an HP12c, and don't know how to use a calculator with an "equal" key. (Well, I know, but it is hard.)

Whirlygig
23rd Mar 2008, 17:34
I started with one years ago (i.e. when I was still at school!!) but I doubt I could go back to one now. Modern calculators (eg Casio) do the sums much as you write the notation which, to me, is more logical.

Cheers

Whirls

Capot
23rd Mar 2008, 17:59
My HP 65 works that way, I think. It certainly has no = key.

It's decades since I used it, but it's still in good order, with all its bits including the programming strips, and I'm thinking of resurrecting it. I think of it as my first computer (1976 or so?).

Flash2001
23rd Mar 2008, 18:08
I've always used RPN calculators from the first HP made. I've tried algebraic calculators and am extremely clumsy with them. They should teach RPN in schools!

After an excellent landing you can use the airplane again!

Whirlygig
23rd Mar 2008, 18:50
Why should they teach Reverse Polish in schools?? It's pretty much obsolete and does not follow notational logical i.e. if I write 2+3=5 and type 2 + 3 = into a modern calculator, I get 5. Simple.

Instead it would be 2 enter, 3 enter, + (I think after 25 years of using one).

Cheers

Whirls

CUNIM
23rd Mar 2008, 19:14
Gordon Bennett, it would be easier to use my old slide rule

Aaaaaaaaaaaaaaaargh!
23rd Mar 2008, 21:00
My calculator is the HP Diversity model. That's the one where ALL the keys are equals.

PPRuNe Dispatcher
23rd Mar 2008, 21:13
I've got a few RPN calculators (all HP), and find them significantly faster to use than "normal" calcs as fewer keystrokes are required for complex calculations.

But that's not their best feature.... the best thing about RPN calculators is that no one else in the office borrows them. Or if they do, they end up doing this : :ugh:

bnt
23rd Mar 2008, 21:20
A friend of mine had a HP41CX, the type that was carried on early Space Shuttle missions, as backup in case their main computers failed... it had "step programming" that bent my brain out of shape, permanently.

HP recently brought out a new RPN model, the HP35s (http://www.engadget.com/2007/07/13/hp-celebrates-35th-anniversary-of-hp-35-launches-35s-calculator/), which started as someone's pet project to mark the 35th anniversary of the original HP35. I thought about it, but I might not be able to use it in university exams, since it's programmable. I went for one of these (http://www.casio-europe.com/euro/sc/technical/fx570es/) instead, which does a lot of stuff I need, like Matrix calculations.

Flash2001
23rd Mar 2008, 22:05
Whirls

Avoids the use of parentheses! Many computer compilers convert to RPN before perforing a calculation.

After an excellent landing you can use the airplane again!

Dushan
23rd Mar 2008, 22:13
But that's not their best feature.... the best thing about RPN calculators is that no one else in the office borrows them. Or if they do, they end up doing this :

Never thouught of it that way, but now that you mention it it is true.

henry crun
23rd Mar 2008, 22:16
There is a HP42S in the house somewhere, left here by my son.

The way it works is a complete mystery to me.

ShyTorque
23rd Mar 2008, 22:42
I had a Sinclair calculator at college, that used RPN. I don't think it worked for very long.

I replaced it with a Commodore SR7919 Scientific calculator. I've just got it from the drawer, put in a battery and it still works, with it's LED display shining brightly.

Just realised it's 34 years old and it's not had a battery in it for about 30 years!

http://i7.photobucket.com/albums/y290/shytorque/IMG_0142.jpg

the incivil beast
24th Mar 2008, 00:27
The Calc98 program (http://www.calculator.org/index.html) that runs on PDAs & Windows can operate in RPN mode

:8 BTW, the limit on the complexity of the expressions you can compute is the depth of the register stack :8

PPRuNe Dispatcher
24th Mar 2008, 11:08
HP has a good webpage describing the advantages of RPN.... (well, they would wouldn't they?)

http://h41111.www4.hp.com/calculators/uk/en/articles/rpn.html

24th Mar 2008, 14:46
I much prefer RPN. I have an HP41C, which my employer bought for me 21 years ago - after I shamed my manager at the time into buying it for me by going into a meeting with a customer carrying a slide rule! The advantage wiuth RPN is when doing complicated calculations involving quantities that need putting in brackets. I do have TI scientific normal algebraic calculator in my workshop - it was £1 in Office World - but I find it incredibly clumsy to use

Out Of Trim
24th Mar 2008, 18:37
I've never tried an RPN type machine...

However this was my first Calculator in the 70's -

http://www.vintagecalculators.com/assets/images/PrinzSR99P_1.JPG

- passed it on to my Father. He's still got it, and it still works!

My second was a nice Commodore - It had very nice tactile buttons I recall..

http://www.vintage-technology.info/pages/calculators/commodore/co1800.jpg

Larry in TN
25th Mar 2008, 19:44
Instead it would be 2 enter, 3 enter, + (I think after 25 years of using one).

Nope, [2] [E] [3] [+]

The real benefit of RPN comes with more complex calculations such as this: (2+3) / (4+5). With a standard calculator you have to calculate the denominator first, store it in memory, calculate the numerator then divide by the number recalled from memory.

i.e. [MC] [4] [+] [5] [=] [M+] [2] [+] [3] [=] [/] [MR] [=] (13 keystrokes)

With RPN it's [2] [E] [3] [+] [4] [E] [5] [+] [/] (9 keystrokes)

ZH875
25th Mar 2008, 20:22
I had a Sinclair calculator at college, that used RPN. I don't think it worked for very long.

I replaced it with a Commodore SR7919 Scientific calculator. I've just got it from the drawer, put in a battery and it still works, with it's LED display shining brightly.

Just realised it's 34 years old and it's not had a battery in it for about 30 years!

http://i7.photobucket.com/albums/y290/shytorque/IMG_0142.jpg

I got my SR7919 in 1977, still going strong, but I have had to replace the battery connector. I also have the slide rule I was issued with in 1977, still barely used, lives in a polythene bag inside the original blue plastic box.

bnt
25th Mar 2008, 22:37
The real benefit of RPN comes with more complex calculations such as this: (2+3) / (4+5). With a standard calculator you have to calculate the denominator first, store it in memory, calculate the numerator then divide by the number recalled from memory.

i.e. [MC] [4] [+] [5] [=] [M+] [2] [+] [3] [=] [/] [MR] [=] (13 keystrokes)

With RPN it's [2] [E] [3] [+] [4] [E] [5] [+] [/] (9 keystrokes)
Sub-standard calculator, more like! On that Casio I linked to, I can do it with 9 keystrokes: [Fraction] [2] [+] [3] [DOWN] [4] [+] [5] [=]

Not that that stops me lusting after a HP50g - I just know I'll spend too much time playing with all its features. At the moment, with university exams coming, "attention conservation" is the name of the game. Why am I here? :8

bnt
26th Mar 2008, 22:23
I should also mention that there's a freeware HP42S emulator for Windows & Mac, called Free42 (http://free42.sourceforge.net/). Looks OK so far. It works on Linux too, they say, though on Ubuntu (Debian) I like grpn (http://lashwhip.com/grpn.html), which is available as standard.

Alpine Flyer
26th Mar 2008, 23:10
There's also a HP42 emulator for Hi-rez Palm OS PDAs. Works nicely but requires a ROM image though which would probably be of dubious origin.

I appropriated my dad's HP15C during my high school years (app. 25 years ago) and also enjoyed that no one else was able to use it. (And the teachers never figured it could solve equations numerically which was nice to have for a cross-check during tests.)

Unfortunately I lost it during my first year on the flight deck and it was never found....