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Which calculator? Hp 50G vs Ti89 Titanium

by sharp
Tags: calculator, ti89, titanium
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ugeminorum
#73
Aug17-07, 09:27 PM
P: 3
Quote Quote by George Jones View Post
Wow!



Do you really mean to argue that different orders of operations apply to -2^4 and -x^4?! This is what you're doing.


The ultimate number crunching software, Fortran, also returns -2**4 = -16. The unary operation of negation is given the same precedence as the binary operation (subtraction) from which its is derived, i.e., -2**4 is the same as 0 - 2**4.

This is incorrect. There are many, many different orders of operations. We choose one order of operations as a communications aid.


My final argument by authority: I asked my wife, and she says that -2^4 = -16. If you want to start an argument by taking it up with her, good luck!!!

PS My wife has a bachelor's in physics, a master's in physics, and a master's in engineering.

NO. Do you understand that -x^4, as written, actually stands for -1*x^4. Go look at an actual mathematics book for reference. So, follow the order of operations; take the four power first, then multiply by -1. If you would like, consult ANY standard algebra text. Wikipedia is not an accepted scientific or mathematical reference, the last time I checked. When it is acceptable to quote from Wikipedia in referred papers, I'll reconsider my stand on this.

I don't consider Fortran to be a final arbiter in this matter, as it was designed for engineers. It also doesn't matter what programming language or brand of calculator does what. I am sure that they all account for their operations. Again, okay if defined up front.

Really, I thought we were talking of the only order of operations that is widely accepted among all Mathematicians when one is taling about the RING of real numbers.

Wouldn't want to argue with your boss. However, I actually have a bachelors degree and masters degree in Mathematics, the actual subject being discussed. I think I am qualified to speak on this topic. I don't think physics and engineering majors quite get into the foundations of Mathematics.
Phykick
#74
Aug23-07, 02:23 PM
P: 2
-2^4=(-2)(-2)(-2)(-2)=

Anyone???












This may be a long day
symbolipoint
#75
Aug23-07, 03:58 PM
HW Helper
PF Gold
P: 2,787
Quote Quote by Phykick View Post
-2^4=(-2)(-2)(-2)(-2)=

Anyone???


This may be a long day
ugeminorum has it right. the exponent 4 belongs to the 2. That part must be evaluated first. [tex] \[
- 2^4
\]
[/tex] indicates the negative of two to the fourth power; note no grouping symbols, so you do the exponentiation first.
[tex] \[
- 2^4 = - (2)(2)(2)(2)
\]
[/tex]
Phykick
#76
Aug23-07, 04:15 PM
P: 2
I thought this was all just levity from all those involved........
The original was (-2)^4 way back in post #13
Please move on from this.

I found this forum looking for info about the HP 50g as my 48 has gone bad.

If anyone has more of the good, the bad and the ugly of the new flavor I would like to here from you.






My degree is in ARTHEYALLINSANEORISITME
dtl42
#77
Aug26-07, 05:20 PM
P: 117
Hey everyone, I've been trying to install the RPN program on my Ti-89 Titanium, and everytime I try to run it, the calculator freezes and I am forced to reset, anyone want to help me through this?
Tom McCurdy
#78
Sep18-07, 10:01 PM
P: 1,113
Ti-89 Ftw
Math Jeans
#79
Sep19-07, 01:27 PM
Math Jeans's Avatar
P: 340
Well, I personally use the Ti-Voyage 200. Its the most advanced thing Ti has got on the market. Thats your best bet for having the functions you want.
271828
#80
Oct3-07, 06:05 PM
P: 1
Well, I'm coming into the thread very late, but have a funny anecdote that might be worth sharing. Full disclosure: I've been an HP calculator fanatic for almost 20 years now and think RPN is the coolest thing since sliced bread, LOL.

Last year, I taught an undergrad class for the first time and had 37 junior and senior engineering students. Every single one of them used a TI-[whatever] and not a single one had an HP. Anyway, on their second exam, they had to solve an equation that took an entire line to write and had three square roots, two of them nested. As I graded it, I noticed that almost every single one of them screwed up punching it through their calculator. Turns out that 3/37 were able to do it without a mistake. Most of them were writing it out in 2-3 lines, etc. I knew I'd catch grief over that, so I punched it through using my HP48G calculator, which is of course RPL (like RPN). I did it three times in a row without an error, averaging 22 sec.!! Of course, I had that ready for them the next class, LOL.

Granted, I was using my calculator when most of them were in preschool, but supposedly younger folks are better at newfangled gadgets, right?

It's hard to explain to non-RPN users why RPN is better, but it really is. I've never met anybody who gave it a fair try for 2-3 weeks who didn't switch over.
becca4
#81
Oct16-07, 11:50 PM
P: 20
I agree. I have the hp 50g and am very happy with it, once I went rpn, I never went back.

Well, I did at times when the 50g's symbolic solving didn't sit so well with the professors, but honestly, it's one of the best investments I've ever made. I'd recommend it for people going into engineering.
Adrian4English
#82
Oct23-07, 02:48 AM
P: 10
I've been using HP's for the last zillion years (or at least since the first HP 35). RPN, when I first met it was confusing but after 10 minutes or so playing with it, it made complete sense to me and I found it easy to use. I have been using HP calculators ever since. Despite my moniker, I'm a professional engineer and would not be without one.
The HP50g is my latest (the last, an HP48sx died on me last year after 20 years of faithful service) and so far the best calculator I have used.
If you like algebraic input, it does have it. Indeed the user manual gives many more examples on how to use algebraic mode than it gives for RPN mode.
My only complaint is that the user manual only brushes the surface of what it can do. The user manual that comes with the machine is some 880 pages long.
You can write some very sophisticated programmes using the built in RPL language but you must know RPN and how the stack operates to use it efficiently.
The ten or fifteen minutes you spend learning RPN is a real investment. Once you know how to use it, you'll never regret it!
stewartcs
#83
Oct23-07, 08:20 AM
Sci Advisor
stewartcs's Avatar
P: 2,283
Quote Quote by sharp View Post
Hey guys, I'm an actuary student and this semester my important math courses are Calculus 2 and Linear Algebra I besides financial math II. I also have calculus 3-4, Linear algebra II, Prob. I-II, and statistics I-II in my future.

Anyway I'm getting a calculator and I can't decide between the Hp50G and the Ti89. I like the infrared and sd flash ports on the hp but I've seen many claim that the 89 is easier to use. Another thing I've noticed is there are more programs available for the 89.

I'm sure most of you know exactly what to look for in a calc. Pleas help me out here, thanks.
Most Calculus courses won't let you use a calculator that perfoms integrals and differentials on exams. You might want to consider that before spending the $$ on either one...or check with your professor to see if they allow them.
SA Penguin
#84
Oct30-07, 08:37 PM
P: 2
Quote Quote by Phykick View Post
I thought this was all just levity from all those involved........
The original was (-2)^4 way back in post #13 Please move on from this.
At the risk of incurring the wrath of everyone, may I point out how this up how RPN is different?

IF you think the minus is part of the number (-2) you solve with: 2 +/- ENTER 4 y^x ...and get 16

BUT- if you decide the - is an operation, and to be done last, you enter: 2 ENTER 4 y^x +/- ...and get -16

The RPN makes no assumptions, it's up to YOU to enter the equation correctly. Whereas the TI made an assumption which sparked this lively debate.

While reading past posts, for some reason I kept thinking of the infamous question - the airspeed of an unladen swallow.
African or European ? (24 mph for European... http://www.style.org/unladenswallow/ )
goodlun
#85
Nov5-07, 02:39 PM
P: 1
Quote Quote by ugeminorum View Post
Apparently, you have not been taught order of operations. Or, more accurately, you have not been taught what is or is not an operation. There is only one operation in the given expression. That operation is the power operation. The base is negative 2.

You mistake the - sign as an operation. It is actually part of the number itself.

As written, the correct answer is 16. Raising a negative number to an even power ALWAYS results in a positive answer.

You should really get your math correct prior to posting.
Wow someone who got it right I think they are confusing Negative(which is a notation) with Minus(which is an operation). Negative means the number is sitting its value left on the number scale of the number 0. Minus means your doing an operation that will move the number to the left of where it is. -2 is a real number we know its the negative value because of the (-) in front of it. While (-1)(2)= -2 the -1*2 operation has already been completed. In the case of -X^4 the actually equation looks like this (-1)X^4 if the value of X was say -2 they the answer would be -16. If the equation was X^4 and the value of X is still -2 the answer is going to be 16.
SA Penguin
#86
Nov5-07, 05:10 PM
P: 2
Quote Quote by goodlun View Post
Wow someone who got it right I think they are confusing Negative(which is a notation) with Minus(which is an operation).
Thank you for your kind words. These operations areindeed different- that's why they have different keys. +/- vs. -.
Without that key, the act of creating a -ve number is harder. If (-2) = (-1)(2) then how do you enter (-1)? The RPN would be:
0 ENTER 1 - *

In an effort to keep the thread moving- which keyboard do you prefer? I've heard people moan about the "feel" of keys, but I also mean the actual LAYOUT. I sure do miss the double-width ENTER key.
Personally, I'd prefer the ON and ALPHA keys be above the actual LCD, similar to my old favorite- the HP41 series. And the 4-way navigation buttons, while nice, take up too much keyboard space.

Comments? Suggestions? Comparisons to TI-89 ?
rs1n
#87
Dec2-07, 08:55 PM
P: 163
I've been a pretty big fan of the older HP calculators (meaning, up the HP 48 series). Many of the examples above explaining why RPN is better don't really capture why RPN truly is a better input method. Forget using nice, whole numbers. In the real world, the numbers we use are almost never that nice.

Suppose you need to work with the quantity, say, x=1.91872163435 (just made this up), and this number appears in your calculations more than once. To speed up entry AND to reduce the possibility of a typo when re-entering the quantity 'x', you may actually want to store this number in the variable 'x'. This takes a few extra keystrokes to do on most algebraic-entry machines, such as the TI89. On an RPN machine, you would simply enter the number once, and DUP (duplicate) it however many times you need to use the number.

Say I want to compute [(3*x+5)^(x-1)]/[(2+7.11)^(3/4)-1], you'd not only have to store the number 1.91872163435 into 'x' (again, to reduce error in inputting and save time), you would also need to close the parentheses in the proper manner so as to not cause problems with the order of operations. On a machine such as the HP48GX, presumably already be in the STACK menu (the '>' means the right arrow, which acts as the SWAP command on the HP48 series):

1.91872163435 ENTER ENTER 3 * 5 + > 1 - ^ 2 7.11 + 3 4 / ^ 1 - /

There is no need for parentheses. There is an added benefit, which many students often take for granted. RPN entry reinforces the order of operations. It is quite sad to see so many undergraduate students fail exams because they still have not mastered the order of operations. Even worse, many students don't realize why their calculator "gives them the wrong answers." RPN essentially forces you to know the rules.

Also, the newer HP50G has both RPN and algebraic entry built-in. Even the older HP48 series had both methods of entry (with algebraic entry requiring exactly one more key, the 'tic' mark, than any TI product).
rs1n
#88
Dec2-07, 09:08 PM
P: 163
Quote Quote by SA Penguin View Post
At the risk of incurring the wrath of everyone, may I point out how this up how RPN is different?

IF you think the minus is part of the number (-2) you solve with: 2 +/- ENTER 4 y^x ...and get 16

BUT- if you decide the - is an operation, and to be done last, you enter: 2 ENTER 4 y^x +/- ...and get -16

The RPN makes no assumptions, it's up to YOU to enter the equation correctly. Whereas the TI made an assumption which sparked this lively debate.

While reading past posts, for some reason I kept thinking of the infamous question - the airspeed of an unladen swallow.
African or European ? (24 mph for European... http://www.style.org/unladenswallow/ )
You are correct in that RPN makes no assumptions. And in this case, there are no assumptions to be made. In terms of the order of operations, there is NEVER supposed to be an assumption. When you see -2^4, the answer is unquestionably -16, and the reason for that is because exponentiation comes before negation (subtraction). On the other hand, (-2)^4 is 16. No mathematician ever writes -2^4 and expect positive 16. Mathematics is precise, and has precise rules. The only ambiguity here comes from not understanding the order of operations.

The TI's distinguis "negative" from "minus" -- this is truly detrimental to students who need to master the order of operations. By using a smaller hyphen for negative, and a longer hyphen for subtraction, the TI's are creating ambiguity for those who are unable to clearly distinguish the lengths of these hyphens. Moreover, they are encouraging poor notation, as students think it's ok to have "-2^4 = 16" because 1) their calculator seems do say so and 2) they can't see the difference between the "negative" hyphen and "minus" hyphen.
rs1n
#89
Dec2-07, 09:25 PM
P: 163
Quote Quote by FrogPad View Post
Ok I put RPN on my 89 and am trying to figure out what makes it so great.

Something I often do with my 89 is evaluate an expression for different values. Let me give an example:

Lets say you have (a+b)/b

Now I want to evaluate this at {a=1, b=2; a=2, b=1} for example:

with an 89 I can do,
(a+b)/b|a=1 and b=2

I can press enter and see a result,
now if I want to quickly change a number I go back to the result screen and press enter,
this comes up: (a+b)/b|a=1 and b=2

I then just change what I want by using the arrow keys,
(a+b)/b|a=2 and b=1

is there a quick way for evaluating expressions using RPN ?
You can write a quick program. And by program, I don't mean you even need to know how to program. The great thing about RPN on an HP48 or HP50 is that you basically write programs by pressing the same keys you'd use in normal operations. A program is encapsulated with << and >> symbols (easily accessed on the keyboard).

Imagine entering in the a and b values separately. If these were your only inputs, how would you compute this using RPN? With a stack, you'd see:

2: a
1: b

First DUP the value b (we'll use it later for dividing) to get:

3: a
2: b
1: b

Then ROT (rotate) the a value to get:

3: b
2: b
1: a

Then + to add, and / to get (a+b)/b.

Thus, to compute (a+b)/b, you would simply do:

<< DUP ROT + / >>

Store this as a variable, and it then becomes part of the variables menu. From this point on, you just enter in your a value, your b value, and press the variable menu key corresponding to your short program.

As another example, if you want to, say, add 10 numbers, you'd simply need:

<< + + + + + + + + + >>

Then you just input 10 numbers (enter all ten separated with space, if you wish) and then press the menu key corresponding to the variable under which you stored the program above.

In sum, the way you enter and compute using RPN converts directly into programs with little to no effort.
rs1n
#90
Dec2-07, 09:40 PM
P: 163
Quote Quote by ugeminorum View Post
So, in the expression -2^4, -2 is not a number. What happened to the negative numbers? If negation is taken purely as an operation, then there are no such things as negative numbers. Whenever I encounter a number with a negative sign, I am to interprut it as a positive number with the negation operation applied? That is the conclusion your logic follows. I, for one, stand by the negative numbers.
Actually, your logic is flawed. If negation is taken purely as an operation, it does not follow that there are no such things as negative numbers. A number with a negative sign can indeed be interpreted as a positive number with a negation operation applied. In fact, this is an equivalent definition of a negative number.

Quote Quote by ugeminorum View Post
In the equation -x^2+16=0, the - is understood to be -1 (- DOES NOT REPRESENT A NEGATION IN YOUR EXAMPLE). Read any elementary high school algebra text. So the equation actually reads -1*x^2+16=0. The solutions are x=4 and -4. This is quite different from -2^4, where -2 is a number. Your answer can only be derived if the expresion is rewritten as -(2^4). There is a big difference. It is not the order of operations you don't understand, it is the actual mathematical notation for which you have no grasp.
The irony here is that it is _you_ who do not understand mathematical notation. When one writes -2^4, it is ALWAYS understood to mean: 2 raised to the fourth power, then negated. This harks back to the equivalent definition of a negative number: -2^4 is the negation of 2^4. That is, -2^4 = -(2^4) as the parentheses here are redundant due to the order of operations. For -2^4, the order of operations say you exponentiate, and then negate. If you want "negative 2 raised to the fourth power" then you MUST use (-2)^4. Here, the 2 is first negated (hence the parentheses) and THEN exponentiated.


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