You enter “((3 * 4) + (5 + 7) * (2 - 1))” into the calculator and then press the enter key; it’s that simple!
I have the fun perspective of someone who is currently enrolled in college as a math maor. On my first day of Calc IV, my teacher asked us if we all had a TI calculator to use. We all did. The same question, more or less, has been asked in every math class I’ve been in since my freshman year of high school. The way the school system is set up, we’re all being trained on algebraic calculators.
I’ve had a TI-83 since I was thirteen, for about six years. I’ve never had any complaints about it. Are the RPNs really that great? How are they with higher level math?
RPNs and the stack logic they use are definintely faster to enter, and especially to perform repeated calculations. As someone else mentioned, the programming logic is also more…well, “natural” if you take Scheme or Forth to be natural.
Also, HP was the first hand calculator (by far) to offer symbolic solution for algebra ad calculus. I believe the high end TIs do this now as well, but at the time HP was the king for this. They have a number of other functions, too, like unit conversions, a wide array of math and programming functions, et cetera, which have since been copied by others. Finally, in my experience (and despite the HP-28S) they are just generally more robust than TIs and other calcs. Extremely high build quality and very resistant to abuse.
And, of course, they are just good for the “nerd factor”…cause MIT and CalTech students were using them first, some engineering schools followed, to be just like the big boys. RPN users tend to be snobbish (yeah, I admit it) just 'cause TIs and Casios don’t rate up in that category. Is it better? Meh. You come to prefer it, and it is (I think) a little faster, but if your TI does the job and you’re happy with it, by all means keep using it.
HP48SX since 1992. I bought it because I wanted portable conversions and formula storage, and had an expansion card with steam table and chemical data on it. RPN was just a bonus (after the first week when I learned how to use it). the only problem, as others have said, is that it’s very hard to go back to a “normal” calc.
My wife would question again and again why I used that “horrible calculator” (same program, 2yr apart) and once when I was going to be away for a week, I said, “Here’s an experiment – use this calc, and ONLY this calc, for one week and then ask me the same question.”
When I got back, she had already purchased her own 48G and got an engraving plate for the backside!
HP-11C Drove my TI-centric teacher crazy (she was also head of the department, and I was her aide. We used to race to see who could do the calculations fastest, so she could “show me”. Heh )
Only a very few students had them (RPN) back then, now I’m bi. I refuse to bring my HP to work, they won’t buy an HP just for me. But the stuff I do now is mostly on computer, I even use the Windows calculator some.
Considering that RPN’s more of an artifact of ancient stack computing technologies (HP adapted Jan Lukasiewicz’s logic system to stack computing) rather than anything super-elegant, I think the argument’s pointless.
People who haven’t used RPN calculators or who aren’t heavily into math will find them kind of confusing.
People who grew up on them (think old engineers) or who do a lot of math tend to like them for either familiarity or the ease that you can do some computations with them, although that’s more a function of Jan Lukasiewicz’s logic system than anything remarkable on HP’s part.
Personally, I prefer algebraic calculators (and I’ve had my share of math- CS major in college; 3 semesters calculus, discrete & combinatorial math and linear algebra). I much preferred being able to enter the equation as it was written, including parentheses, so that I could edit it if I got something wrong. My old Casio graphing scientific calculator let me do that.
bump, RPN is not merely an artifact. It is a way of doing things that many people prefer over algebraic. You don’t like it and that’s fine, but to think your personal preference is a law of nature or technology is wrong.
You are right, however: The argument is pointless. RPN is the best way to do things.
I got you all beat. I got my first hp in 1973 (an hp35) at a cost of $300 (to put that in perspective my college tuition that semester at a private school was $650). I still have the calculator, the power cord, the leather case, the instruction manual and the plastic case to put it all in. All that I’m lacking are the rechargeble batteries. It still works like a charm.
When my kids went to hs I got them RPN hp’s as well. My daughter’s idiot math teacher had the nerve to tell her that she couldn’t use the calculater that I bought her, an hp48G, because it wasn’t a “scientific calculator” We had several discussions before she “let” her use such an unscientific calculator
I cannot figure out how to use TI’s. This slide rule trained brain just likes to do operations in the appropriate order. :wally
OK, algebraic calculators work the same way you write out an equation, I’ll give you that.
For me, RPN is closer to the way I think. When you read the above example and figure out what it’s doing - or when you look at the original problem that gave you that calculation - you don’t think linearly from left to right. You think from the innermost parentheses to the outermost. At least I do. And that’s how RPN works.
I haven’t used it for high level math though. Higher math usually doesn’t involve numerical calculations, do they?
I got sold on RPN the first time I tried to balance a checkbook with an algebraic calc. I type in my opening balance press minus then the first check, them minus and the second check, minus then the third check. All is fine and good till I hit minus and realize that the next number is a deposit. :smack:
To my feeble mind this means I am always having to think 1/2 step ahead. (that next number is it a check or a deposit?) With RPN I say to the calc here are the two number now add them (or subtract or what ever)
xiao I actually did kind of lose it. The worst part was the teacher didn’t understand the concept of “order of operations.” The entire year she gave my daughter a hard time about her unscientific calculator and expressed surprise!! that she could get the right answers with it What a doofus :rolleyes:
Stranger on a Train,
"Eh? I don’t think that’s right. I’ve had a number of HP RPN calculators, and they’d all handle that just fine. I just checked it on my 48G, and it gives the correct answer. "
You sure? Because I just checked it myself. My HP 32SII returns 6 and my 28S returns 4.
For that matter, what do you think “correct answer” means?
What’s the role of the Enter key in RPN? Is it simply to separate numbers, as in 5 Enter 6 rather than 56? Because HP decided to do something else with it, namely, to duplicate what’s in the X register. But then they added stack lift enable/disable, so you could use Enter which duplicates X and then overwrite X with the next number you enter. However, in Forth, there is no “enter”. You’d use whitespace to separate numbers. The 28S comes closer to the Forth version. What we’re talking about here isn’t a bug, it’s disagreement about a subtle point, involving how best for the interface to work.
Well, obviously the correct answer is 4. On my 48S (which, like the 28S, displays multiple elements of the stack on screen) hitting the <enter> key after entering the second digit in your example just closes the stack entry. Hitting it again will duplicate it, but that is by design. I’m mortally certain the 32S worked the same way, and I don’t remember having the described problem on the ex-wife’s 11C, though it’s been so long and I used it so infrequently I can’t really say for certain.
It seems the convention with HP “RPN” has changed over time, to a definition that is more consistent with a standard understanding (per Forth) of how RPN should be implemented.
FTR, My 28S and 48S allow “full” entry (enter key after each stack element), incomplete entry (no enter key between last argument and command execution), whitespace entry (all arguments on one line, seperated by spaces), or algebraic entry via use of the single quotation brackets (and the Equation Editor). Let’s see the TI match that!
I don’t know about these new-fangled HP’s, though…the 49sII and so forth. They look a little like kindergarden toys to me. Oh well, at least they reversed their pledge to stop making calculators at all.
Stranger, I don’t think it’s at all obvious that the correct answer is 4. It depends on just exactly what the different keys are all supposed to do.
Your comments about your 28s and 48s allowing “full” entry sound correct and, moreover, detailed and insightful.
In my understanding HP had a different idea earlier on, and I think I remember some HP manual pointing out that you can calculate e.g. the square of 13 by typing
13 Enter *
which is meant to be a convenience. It isn’t incorrect, if that’s what they intended it to do. Maybe I’ll find this reference.
In the meantime, they apparently did once intend this “Enter does dup” convenience, at least on several models. I just tried
1 Enter 3 Enter +
on my HP 15C, and got a 6. I think the 15’s another one from the “convenience” age.
I think I read a discussion on the issue - maybe I can find that too.
To summarize my understanding, there were two different mental pictures of what an RPN calcular ought to do - and no malfunctions AFAIK. But a cite would be most welcome here…
Here we go - found a cite. The calculator described here should return 6 if you type 1 Enter 3 Enter +. This amounts an alternate version of “correct”.
{Quoted from HP 32SII RPN Scientific Calculator Owner’s Manual, p. 2-6}
How ENTER Works
You know that [ENTER] separates two numbers keyed in one after the other. In terms of the stack, how does it do this? … [ENTER] replicates the contents of the X-register into the Y-register. The next number you key in (or recall) writes over the copy of the first number left in the X-register. The effect is simply to separate two sequenially entered numbers.
Using a Number Twice in a Row
You can use the replicating feature of [ENTER] to other advantages. To add a number to itself, press [ENTER] [+].
