Which calculator?

[Tark62]

I can see faster, but how is it more intutive? I'm not arguing, just honestly asking. Take 2 + 2 = 4.
I just don't see how 2, 2, ENTER is more intuitive than 2, +, 2, =

How did you add two numbers in elementary school? Probably like this:

(1) You wrote down the first number on a piece of scratch paper;

(2) You wrote down the second number underneath the first number;

(3) You performed the addition

An HP-33S or HP-35S calculator works in exactly the same way, like you were using scratch paper:

(1) You input the first value, followed by ENTER, which raises the first value to the upper line of the display;

(2) You input the second value, which goes underneath on the lower line;

(3) You press + to perform the addition.

If you've ever solved math problems with scratch paper, then you should be able to "get" RPN. It's just virtual scratch paper.

Ultimately, the preference for RPN vs. algebraic comes down to a "philosophical" difference in problem solving, which becomes more pronounced as equations become more complex. Suppose you have a large complicated equation -- would you rather solve it as one big problem, or as a series of small problems?

Modern algebraic calculators are optimized for the "one big problem" approach. They allow the user to input very complex equations, which can be formatted exactly as they would be in a textbook. This approach will work, as long as you've copied the equation perfectly. However, some people feel that this approach encourages copying rather than thinking, and that it may lead to undetected errors if the equation has not been copied or understood perfectly.

RPN calculators, in contrast, are optimized for the "series of small problems" approach. RPN does not allow pending operations or expressions in parentheses: the user is forced to think through the equation one step at a time (as with scratch paper), and sees all intermediate results (as with scratch paper). Some people are more comfortable solving complex problems this way, as opposed to doing it in one big step.

 

[Sschell]

^yeah... take that!

 

[Dleg]

ZZZZING!

 

[mudpuppy]

There's nothing that says you have to do problems in one big step with an algebraic calculator. I do calculations of the following form quite often in my work:

46^2/(1.5*40*cos(75-arccos(.9))

However, I don't enter it this way in my calculator. I do this: 46^2/1.5/40/cos(75-arccos .9 =

To me this is perfectly logical and I can type it in quickly, whereas I wouldn't know where to start with RPN.

 

[Katiebug]

I decided to get the HP 33s, and my father in law (a math teacher) is getting me one of the TI calculators on the list for free, so I can try out both. I do love TIs, but I like the idea of an equation solver like the HP has.

 

[Dleg]

The 115ES also has a solver function. Not sure if the HP works better, though. The few times I tried the solver function on the 115, it chugged away for literally several minutes, and once did not even have a solution (an engineering economics problem of a variety you are NOT likely to ever see on the PE exam). But it generally worked for solving Manning's equation for diameter or depth of flow, although I genuinely believe that just back-plugging the four possible answers (on a multiple choice question) into the equation is faster. And safer - at least then you know what you are doing.

 

[Tark62]

There's nothing that says you have to do problems in one big step with an algebraic calculator.

No, of course not. But if you like to solve problems in step-by-step mode, then RPN calcs can do it more efficiently and (for most people) more easily. They are designed to work that way, and algebraic calcs aren't.

Your "perfectly logical" example demonstrates this point. For example, it isn't actually step by step: it looks like the final "cos 75-arccos .9" expression contains multiple pending operations, which are evaluated "all at once" with the final press of the = key. The reason for doing it this way is presumably to avoid using closing parentheses. The example also includes some rather significant alterations to the original equation: two multiplications were changed to divisions, again presumably to avoid the use of parentheses.

It appears that you are prepared to go to some lengths to avoid parentheses and pending operations (although you were not totally successful in this case). If that's the way you like to calculate, then maybe you should give RPN a try. The same expression can be solved with RPN without changing any of the operations, without the need for any parentheses, while showing every intermediate result, and using the same number of keystrokes.

 

[Tark62]

The 115ES also has a solver function. Not sure if the HP works better, though.

My impression is that the Casio and the HPs all have decent equation solvers. The HPs have the advantage, though, because you can store commonly used equations (e.g. time value of money, Manning's equation) and recall them, rather than re-entering them every time. This capability is the basis for the "33S Essential Equations" books published by the other board.

Whether this feature is really helpful on exams is another issue, because most of the equations on NCEES exams are simply not that complex. I do think that economics problems can be solved faster if you have a calc with a pre-programmed time value of money equation, rather than using the lookup tables in the FE handbook.

 

[EM_PS]

The casios are my choice for alot of the same things Brody already said. The HPs are the most robust (most $$ too), and are programmable. But do you really want to scroll thru a single letter defined set of program names, versus just working with what you know, and using the casio in the SOLV mode, maybe even back solving for the answers given as Dleg mentioned. In addition to this board, check out the reviews of the various calcs on Amazon. seriously, the reviews on the HP-33 totally scared me away from it.

I understand RPN, just don't understand why people are so fanatical about it. Its like for the fans of it, you all are so passionate(!) about it - but for ones who don't care for it, no biggie, just do the algebraic thing.

I use alot of Excel, and mathcad, and matlab, and even visual basic - and no virginia, none of those venerable software platforms remotely have any logic approaching the RPN lmethod of problem solving. I like my method of problem solving to be fluid, whether punching a calc, or writing code in MatLab.

 

[Katiebug]

My impression is that the Casio and the HPs all have decent equation solvers. The HPs have the advantage, though, because you can store commonly used equations (e.g. time value of money, Manning's equation) and recall them, rather than re-entering them every time. This capability is the basis for the "33S Essential Equations" books published by the other board.
Whether this feature is really helpful on exams is another issue, because most of the equations on NCEES exams are simply not that complex. I do think that economics problems can be solved faster if you have a calc with a pre-programmed time value of money equation, rather than using the lookup tables in the FE handbook.

The economics equations are going to be programmed in. Despite having a master's degree in management, I can't remember those formulas to save my life! There are a few others that I think will be helpful, too.

I don't use the equation solver all that often on my TI-89, but when I do use it, I like it. The TI calculators allowed by NCEES at the moment don't have a solver, at least not one that I've seen referenced in the specifications.

Yeah, the FIL can get me any TI calculator for free, so I'm just going to try both and see which I feel more comfortable with. I have the feeling the HP is going to stay in algebraic mode...RPN just doesn't make sense, although maybe it will if I try it.

 

[Dleg]

Well, having used both RPN and regular (for the PE exam, too), I can say with some authority that neither mode is "superior". They both work well. I recall liking RPN better after becoming proficient at it. But I was very impressed with the capabilities of my Casio 115ES by the time I learned its deepest workings, like the statistical operations.

But look at it this way: Studying for one of these exams is perhaps the perfect, and perhaps only opportunity you are ever going to have to really "learn" a new calculator, so why not go for RPN? It's the ultimate badge of engineering prowess (I was going to say geekiness, but thought better of it).

But please, if you're going to take a stab at RPN, just go for the new HP 35s, and not that piece of crap 33s.

(I've never used a 33s so I have no idea what I am talking about in that regard! But the 35 is very nice. Even comes with a DVD about the history of HP calculators. )

Don't forget that whole programmability thing - it makes the HP more versatile after the exam (of course I haven't used it yet, in a year and a half now).

 

[RIP - VTEnviro]

If you've ever solved math problems with scratch paper, then you should be able to "get" RPN. It's just virtual scratch paper.
Ultimately, the preference for RPN vs. algebraic comes down to a "philosophical" difference in problem solving, which becomes more pronounced as equations become more complex. Suppose you have a large complicated equation -- would you rather solve it as one big problem, or as a series of small problems?

OK, I get that response. That makes sense.

I philosophically like to write out the whole equation on paper before I attack the calc.

And you can do a large complex problem in algebraic notation. Most calculators these days store the previous answer or two and you can do the calc in steps.

I often do that rather than input a giant equation for the exact reason of avoiding an input error.

More than 1 way to skin a cat I suppose!

 

[TXengrChickPE]

How did you add two numbers in elementary school? Probably like this:
(1) You wrote down the first number on a piece of scratch paper;

(2) You wrote down the second number underneath the first number;

(3) You performed the addition

I dunno... maybe I'm weird (well, I KNOW that I'm a little strange sometimes) but when I added 2 numbers in elementary school, I did it like this:

1) Write first number

2) Write a + sign below and to the left of the first number

3) Write second number next to the + sign

4) Underline the bottom line

5) Perform the addition

Which correlates exactly to how I enter the information on my algebraic calculator:

1) Key in first number

2) Press + sign

3) Key in second number

4) Press = button

5) Calculator performs the addition

Don't get me wrong, I did use RPN for several years and liked it... I just don't agree that it is "intuitive" in any sense of the word!

 

[RIP - VTEnviro]

^ I agree with TX 100%!

I think the reason I'm such a big Casio fan is because of the 'just like on paper' method of inputting the arguments.

 

[ODB_PE]

Even comes with a DVD about the history of HP calculators.

Is it lame to want to watch that DVD? Netflix doesn't have it yet. What to do (except for buy the 35s?)

Added - HP has about an 8 minute video online - the same thing?

 

[Capt Worley PE]

Is it lame to want to watch that DVD?

I'm in trouble if it is.

 

[Guest]

Oh boy .. I can see this thread is heading for the Hall of Fame!

Argument is going to dwindle to ...

Tastes Great !!

........................... Less Filling !!!

:bananalama:

JR

 

[RIP - VTEnviro]

I was always a less filling guy.

 

[maryannette]

TASTES GREAT!!

 

[Tark62]

when I added 2 numbers in elementary school, I did it like this:
1) Write first number

2) Write a + sign below and to the left of the first number

3) Write second number next to the + sign

4) Underline the bottom line

5) Perform the addition

Admittedly, that way will work, but it turns out that Step 2 is completely unnecessary. You can skip it and save a step, while still adding the numbers correctly. Try it on a piece of scratch paper and you'll see !