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What Is RPN? Why Did/Does HP Use RPN? Learning RPN (1999)

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Re: What Is RPN? Why Did/Does HP Use RPN? Learning RPN (1999)

#91

Post by briffle »

dheera wrote: post #74
pcardoso wrote: post #39

When I was starting my degree (around 96) I went to the US for a week and bought a HP48Gx since they were cheaper there. This happened a few weeks after a Swiss jet crashed departing NY and the reasons were not known at the time so the airport staff was very suspicious. When they saw the calculator and tried to do a simple test calculation and failed, I struggled to explain how use it, since it was also so new to me.…

HP48GX was the best calculator ever. I used one throughout my middle/high school. The best features, IMO, were (0) the IR emitter and (1) the ability to program it to switch ON at a specified time and run code. This means I could hide my calculator somewhere in a room before class started and program it to turn on halfway through class, turn the classroom TV on, turn the volume to max, and start wildly flipping to ra…

I bought mine in 96, when I was still in high school, and sold it around 2008 for more than I bought it for. But I miss it.

Re: What Is RPN? Why Did/Does HP Use RPN? Learning RPN (1999)

#92

Post by ece »

I got an HP48G in high school for UIL[1] competitions at the direction of a math teacher, and once I got the hang of it, it's been hard to use anything else. The competitions were a mix of math and seeing how many problems you could go through in 30 mins using a calculator. Pretty fun once you get the hang of it, and the HP48G/RPN did give me more time on non-numerical problems. The IrDA is finicky, but the programming and builtin features are great. The feature set is a bit much for a high school student maybe, but I used it through all of college too. I probably played a bit more minesweeper on it than I should have.

The HP prime and Droid48 apps are nice, but I just don't need calculators as much anymore.

[1] https://www.uiltexas.org/academics/stem/calculator-applicati...

Re: What Is RPN? Why Did/Does HP Use RPN? Learning RPN (1999)

#93

Post by woofie11 »

dehrmann wrote: post #85
aseerdbnarng wrote: post #13

I was forced to use an HP12C as part of my university degree. Once you get used to RPN it’s quite uncomfortable to switch back. It’s a much more intuitive way to do math once you get over the small hurdle. 15 years later and I’m still using the same calculator!

> It’s a much more intuitive way to do math Is it? It's easier to code an evaluator, but I'm not convinced it's necessarily more intuitive. In practice, only addition/subtraction and multiplication/division are ambiguous. I'll also play devil's advocate and admit order of precedence is somewhat arbitrary, and precedence of bitwise and and equality is wrong in most languages. Not sure why I'd want this: (flags & (4 ==…

Yes. It is.

One difference is you see all intermediate results. That's huge for avoiding mistakes. In-fix, if you type (5+5)*(9+9), you only see the end result. Post-fix 5 5 + 9 9 + *, you see 10 and 18 along the way.

Another is the stack lets you easily reuse subresults. If you've computed the total energy and want to use it three places, you pick it off of the stack. All your work is there. It's very common that this happens.

It's an incredible productivity boost once you get used to it.

Re: What Is RPN? Why Did/Does HP Use RPN? Learning RPN (1999)

#95

Post by taeric »

tzs wrote: post #44
jjav wrote: post #32

Earlier quoted context omitted.

RPN is so nice and efficient, can't imagine using anything else. I like that the OSX calculator does RPN. But mostly I use my old 28S which is next to my keyboard always. Also have a 50g on the desk, but I prefer the 28S.

I get annoyed by the ways the OS X calculator deviates from HP RPN. The main one is that the pi and e keys act as if they are invoking constant functions that return pi and e, respectively. On an HP calculator, the pi key enters pi. That may sound like the same thing, but it is not. Consider this sequence: 2 ln pi x On my HP 15C the result is to multiply the natural log of 2 and pi. Same thing with PCalc on my iPhone…

That sounds like a bug. Why would any value replace the top of the stack?

Re: What Is RPN? Why Did/Does HP Use RPN? Learning RPN (1999)

#96

Post by kqr »

dehrmann wrote: post #85
aseerdbnarng wrote: post #13

I was forced to use an HP12C as part of my university degree. Once you get used to RPN it’s quite uncomfortable to switch back. It’s a much more intuitive way to do math once you get over the small hurdle. 15 years later and I’m still using the same calculator!

> It’s a much more intuitive way to do math Is it? It's easier to code an evaluator, but I'm not convinced it's necessarily more intuitive. In practice, only addition/subtraction and multiplication/division are ambiguous. I'll also play devil's advocate and admit order of precedence is somewhat arbitrary, and precedence of bitwise and and equality is wrong in most languages. Not sure why I'd want this: (flags & (4 ==…

> Not sure why I'd want this: (flags & (4 == 4)), but that's what flags & 4 == 4 does.

Originally there was no && operator. You had to use & for Boolean conjunction too. The precedence makes sense under that condition. (And later couldn't be changed without breaking existing code.)

Re: What Is RPN? Why Did/Does HP Use RPN? Learning RPN (1999)

#98

Post by glandium »

briffle wrote: post #91
dheera wrote: post #74

Earlier quoted context omitted.

HP48GX was the best calculator ever. I used one throughout my middle/high school. The best features, IMO, were (0) the IR emitter and (1) the ability to program it to switch ON at a specified time and run code. This means I could hide my calculator somewhere in a room before class started and program it to turn on halfway through class, turn the classroom TV on, turn the volume to max, and start wildly flipping to ra…

I bought mine in 96, when I was still in high school, and sold it around 2008 for more than I bought it for. But I miss it.

Droid48 to the rescue.

Re: What Is RPN? Why Did/Does HP Use RPN? Learning RPN (1999)

#100

Post by 082349872349872 »

m463 wrote: post #19

Reading these comments, I'm surprised that people think in RPN. (I mean I shouldn't be, I just didn't think of it) I wonder if teaching it early on, instead of parenthesis, would have made math lessons different? Could there have been different notations used for things like factoring out a quadratic equation?

Even algebraic has different also-possibles. APL and Smalltalk don't bother with precedence, for example.
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