Calculators Which calculator? Hp 50G vs Ti89 Titanium

[bfr]

I know this is kind of an old thread, but I registered on these forums just to reply to it. -2^4 should be -16 by order of operations; 2^4 is evaluated first, and it is 16, and then the opposite of it is taken. Powers/exponents come first - the TI-84+ SE was correct.

And, although HP (and Casio) calculators have many good features and are good for certain things, there seems to be an overal dislike of TIs, particulary the TI-89 Titanium here. A few issues:

- Some TI-89 programs aren't compatible with the TI-89 Titanium
> That can be fixed by installing a simple patch at www.ticalc.org. Many TI-89 programs still run on the TI-89 Titanium without a patch anyway.

- The TI-89 Titanium is slow
> This is hardly ever an issue. The TI-89 Titanium has been able to run grayscale 3-D games without any speed issues. Plus, a new TI-89 Titanium hardwar 4 has been released with offers a slightly faster CPU.

Also, there are many, many programs for the TI-89 (and the TI-89 Titanium), particularly at www.ticalc.org, if something isn't built-in, it can usually be downloaded. The TI-89 Titanium also has very advanced symbolic manipulation, and can simplify, expand, and manipulate all sorts of math, from trigonometry to calculus.

So, although the Hp 50g may have more RAM and a faster CPU (has the faster CPU ever really been taken advantage of anyway), the TI-89 Titanium is probably better for mathematics courses. Anyway, the first post in this thread contained: "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." This probably would indicate that he/she was interested in a calculator particularly good in mathematics and that would have good education support.

Just to clarify, the HP 50g is pretty good and is better than the TI-89 Titanium in many ways, but it just seemed that the TI-89 Titanium was being looked at unfairly.

 

[odobo]

"What's wrong with a pen and paper?

Kids these days...

<wanders off grumbling to oneself>"


If you can integrate, for example, e^(-x^2) from 0 to 8 without a calculator or computer, then I guess you don't need one. But for most people, calculators save time.

Rpn alone makes hp superior, but rpn serves as a solid foundation for building powerful tools. In sum, hp built calculators for engineers and professionals and for use in the real world, and ti builds, well, toys for children.
Do you use a steel hammer to build a house, or do you use a childrens plastic toy hammer?

Just look at the resale value of old hp calcs on ebay. I saw an hp 15c go for 430 dollars. People that have used hp know their quality, and will pay ridiculous prices to get their favorite tool.

No one will EVER pay that much for an old ti, even if it still works.

 

[Danger]

I readily admit that I skipped all but the first page of this thread. Too damned many numbers in it.
All that I want to ask is: Why would you buy a calculator of any sort when you can get a laptop with calculator software for the same price or less?

 

[FrogPad]

... for the same price or less?

A TI-89 is ~200.00 (USD)

A cheap laptop is ~500 (USD).
A calculator is very convenient to use when compared to using more complex math programs. It is often useful when prototyping an answer to a problem. A calculator will have orders of magnitude more battery life than a laptop. Each serve a purpose.

 

[bfr]

"A TI-89 is ~200.00 (USD)" -> More like 150.00 these days. Calculators are even more portable than laptops, as portable as laptops are, and plus, they are probably allowed on more tests.

EDIT: Oh, and I think I'm missing something - what's so good about RPN? From what I can tell, it doesn't really seem more powerful or easier into enter, and I don't see how RPN alone would make HP superior. Could somebody please kindly explain the advantages of RPN? (And note that there is a program that let's the TI-89 have RPN)

 

[Danger]

A TI-89 is ~200.00 (USD)

A cheap laptop is ~500 (USD).

Ahhh... I'm not sure about calculators, but if you don't mind using one of those Windows-burning pieces of ****, you can get a Pentium 4 laptop for $350 CdnD, which is probably about $320 USD at today's exchange rate, where I live. The good stuff, unfortunately, runs a bit steeper.

 

[FrogPad]

Ahhh... I'm not sure about calculators, but if you don't mind using one of those Windows-burning pieces of ****, you can get a Pentium 4 laptop for $350 CdnD, which is probably about $320 USD at today's exchange rate, where I live. The good stuff, unfortunately, runs a bit steeper.

True that. A Pentium 4 would run what can be done (and a lot more) on a calculator just fun.

I would just vote for convenience than. I can easily have my calculator on me at all times, it is not so easy to take a laptop around.

Plus, with heightened security at the airport ... just kidding

 

[ranger]

EDIT: Oh, and I think I'm missing something - what's so good about RPN? From what I can tell, it doesn't really seem more powerful or easier into enter, and I don't see how RPN alone would make HP superior. Could somebody please kindly explain the advantages of RPN? (And note that there is a program that let's the TI-89 have RPN)

This has been discussed already.
https://www.physicsforums.com/showthread.php?t=157962

If you're still unclear about RPN, feel free to resurrect that old thread.

[And yea, that $200 USD is an exaggeration of the current price]

 

[ranger]

Ahhh... I'm not sure about calculators, but if you don't mind using one of those Windows-burning pieces of ****, you can get a Pentium 4 laptop for $350 CdnD, which is probably about $320 USD at today's exchange rate, where I live. The good stuff, unfortunately, runs a bit steeper.

I think you're relying too much on the forum censorship software You could have said **** and kept the angry vibe.

EDIT: OK then, probably turd

 

[FrogPad]

This has been discussed already.
https://www.physicsforums.com/showthread.php?t=157962

If you're still unclear about RPN, feel free to resurrect that old thread.

[And yea, that $200 USD is an exaggeration of the current price]

Damn. Those things have dropped in price.

 

[Danger]

Plus, with heightened security at the airport ... just kidding

It's not really that funny. I know that if I were an airport security officer, I'd never let anyone with the last name of 'Pad' onto a flight. You're obviously a terrorist.

 

[jkotecha]

TI89 vs 50G

I have both TI89T and 50G. I bought the 50G first because I'm use to RPN (12C, CX, SX). I had a lot of problems with the 50G. Basic keys that should be on the keyboard have been removed. I did a lot of customization. Then
I started to find other issues. E.g. no true support for vector transpose, slow integration, lack of programming support.

A friend of mine turned me on to the TI89T. He was a HP buff, but moved to TI89T. Now he uses a free 3rd party RPN. He has a 3rd party equation writer, but once you see how easy and powerful the 3rd party RPN is you wonder why you bothered loading the EQW.

For typical problems, I'm finding the TI89T to be faster data entry, faster results. For example, $(x/(x^2+y^2), dx) take the TI89T < 1 second. Its so fast I don't even know how to time it. With the HP50G, it takes about 4 - 6 seconds.

For pathological cases, but TI89T and HP50G do badly. For example, try
$(sin(x)/x, x, 0, inf). Both calculators give up. The HP50G returns with the wrong answer. The TI89T keeps "BUSY". You basically have to QUIT. I don't know what's better, getting the wrong answer or getting a "BUSY". I suppose if you don't know the answer, getting the wrong answer might be a problem.

I think more people should know that there is a 3rd Party RPN utility. The debate between TI89 and HP50G would become very interesting.

 

[FrogPad]

It's not really that funny. I know that if I were an airport security officer, I'd never let anyone with the last name of 'Pad' onto a flight. You're obviously a terrorist.

that really is my last name

 

[Danger]

...[/color]

 

[FrogPad]

...[/color]

wink ...[/color]

 

[berkeman]

It's not really that funny. I know that if I were an airport security officer, I'd never let anyone with the last name of 'Pad' onto a flight. You're obviously a terrorist.

I don't get it. But then again, I haven't read much of the thread. And then again, I also know very little about terrorists. What's the joke?

 

[chrisakel]

I have only used the TI-89 and its been good to me.

 

[Danger]

What's the joke?

I probably shouldn't respond to this, since I just got a PM from Jkotecha giving me **** for not staying on topic, but since you're a Mentor and he's not...
It wasn't really a joke; just sniping at the concept of racial profiling. If someone named Rajid is obviously a terrorist to the US government, then someone named Pad is obviously one to me. The whole point was that there is no point.

 

[ugeminorum]

-16



which is correct




which is incorrect.

Have you not yet been taught the conventional order of operations?

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.

 

[George Jones]

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

Negation is an operation; it's an example of a unary operation.

As written, the correct answer is 16.

No, according to the standard order of operations, -2^4 = 16.

There is no law that prohibits a company from marketing calculators or computer software (e.g, Microsoft Excel) that use a non-standard order of operations, but I think it is silly to do so.

This reminds me of a joke I once read. How many Microsoft employees does it take to change a burnt-out lightbulb? None. Microsoft declares darkness the standard.

A standard order of operstions aids communication; if everyone follows the standard, then everyone knows what a given expression means. In the standard order of operations, the power operation takes precedence over negation.

As an example, consider the equation

-x^2 + 16 = 0.

According to the standard order of operations, x = -4 and x = 4 are solutions to this equation. According to your non-standard order of operations, x = -4i and x = 4i are solutions to this equation, which seems quite bizarre.

I applaud TI for using the standard order of operations. Maple also follows the standard order of operstions and returns -2^4 = -16.

Raising a negative number to an even power ALWAYS results in a positive answer.

Agreed.

 

[ugeminorum]

-16



which is correct




which is incorrect.

Have you not yet been taught the conventional order of operations?

Negation is an operation; it's an example of a unary operation.



No, according to the standard order of operations, -2^4 = 16.

There is no law that prohibits a company from marketing calculators or computer software (e.g, Microsoft Excel) that use a non-standard order of operations, but I think it is silly to do so.

This reminds me of a joke I once read. How many Microsoft employees does it take to change a burnt-out lightbulb? None. Microsoft declares darkness the standard.

A standard order of operstions aids communication; if everyone follows the standard, then everyone knows what a given expression means. In the standard order of operations, the power operation takes precedence over negation.

As an example, consider the equation

-x^2 + 16 = 0.

According to the standard order of operations, x = -4 and x = 4 are solutions to this equation. According to your non-standard order of operations, x = -4i and x = 4i are solutions to this equation, which seems quite bizarre.

I applaud TI for using the standard order of operations. Maple also follows the standard order of operstions and returns -2^4 = -16.



Agreed.

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.

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.

It is okay for TI and Maple to handle the expression the way the do, as long as it is documented.

And, for your infomration, I am following the ONLY order of operation.

 

[George Jones]

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.

Wow!

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.

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

It is okay for TI and Maple to handle the expression the way the do, as long as it is documented.

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.

And, for your infomration, I am following the ONLY order of operation.

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.

 

[ugeminorum]

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]

What the?

-2^4=(-2)(-2)(-2)(-2)=

Anyone?












This may be a long day

 

[symbolipoint]

-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. \[<br /> - 2^4 <br /> \]<br /> indicates the negative of two to the fourth power; note no grouping symbols, so you do the exponentiation first.
\[<br /> - 2^4 = - (2)(2)(2)(2)<br /> \]<br />

 

[Phykick]

Post #13

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]

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]

Ti-89 Ftw

 

[Math Jeans]

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]

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]

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]

HP50g

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]

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]

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]

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]

Twisting The Topic a bit...

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]

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]

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]

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]

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.

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.

 

[bfr]

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).

I don't know of any TI calculator that says or seems to indicate that -2^4=16.

 

[rs1n]

I don't know of any TI calculator that says or seems to indicate that -2^4=16.

Yes, you can get -2^4 = 16 if you use type "negative 2 ^ 4" using the (-) key as opposed to the "minus" key. Otherwise, I have several defective TI-85's.

 

[bfr]

Well, I don't have a TI-85 nor an emulator to confirm that, but I do have a TI-84 Plus Silver Edition, TI-86, Ti-89 Titanium, and a Voyage 200, and none of them will give me -2^4=16 by doing what you said. Maybe you're using an outdated operating system? The TI-85 itself is old anyway and is no longer really supported by TI. If it does really return 16, though, then that is pretty bad (I'm trying not to be biased towards TI calculators).

And, although I don't have a HP calculator to try RPN with, I did try an RPN calculator on the computer, and it didn't seem to be any faster. I probably have to get used to it, but still, it didn't seem like I was pressing less buttons or it was any more efficient. The way expressions are entered in TI calculators is also more similar how they would be written down on paper, which consequently would probably make it easier to copy expressions from a textbook or something. Also, note that there are programs for TI calculators that let expressions be entered in RPN..

Maybe I just don't how to use RPN efficiently and am not putting it to its potential, but I've read a lot about it and have experimented with it, and it didn't seem to be that good. Or, again, maybe I just need more experience with it.

 

[rs1n]

As far as I can tell, this does not show up in any of the recent TI calculators -- which is great. In that light, I don't have a problem with the distinction between (-) and - anymore with the TIs.

Regarding the book-like entry method, the HP48 (now more than 15 years old?) had the ability to enter in equations just like shown in the textbook via the Equation Writer. Granted, it is extremely slow compared to more modern calculators, but in the HP50G it should just as quick as competing models.

It's hard to get a good feel for RPN on a computer or emulator, in my opinion. The main reason is that you're using a computer keyboard for entry, which is MUCH easier to use than a custom (and to some, tiny) keyboard.

Regarding programs that enable RPN -- I think that's fantastic. However, I usually evaluate calculators based on their factory settings. With added software, it seems reasonable to assume that with enough memory, any calculator can be made equal to a competing model. The HP50G uses SD cards with capacities of up to 2 gigabytes. Its specs are at least comparable to any competing model. So one could argue that anything it lacks can be made up through software additions.

Back to RPN -- the main reason I support RPN is that it reinforces the order of operations. It is quite disappointing to see incoming undergraduates continually make mistakes having to do with order of operations. One would think that with that much education, something as basic as middle school mathematics should be mastered at that point.

 

[Phred101.2]

An aside, but perhaps relevant to undergraduate math skills. I've met 3rd yrs who seem to have very poor English comprehension. I was asked once by such a student if I knew the difference between a noun and a verb. I didn't know what to say. In the end I said little, but I was thinking "it's probably a bit late now, dude, what do you expect me to tell you?"...

Education at the high school level appears to be slowly going down the tubes.

RPN is generally a lot fewer keystrokes and you keep an intermediate result, so you can look at the first part of some eqn. or formula and see if it looks like what it should, etc. Stack-based calculating just seems more natural somehow, once you get the hang of it (which took me about a day when I got my first HP calc, well, a few hours over the course of a day).

 

[choldstare]

Hello! I am a sophmore year EE student who was in the same dillema as the OP. I went with the HP 50g. Now when people say you can't go wrong with the ti 89 they are absolutely correct. They are widely used and easy to figure out how to use. Now I was very excited about getting the HP 50g. I took a chance and said everyone has a 89 but i hear the hps are very good. And this time i was right. The RPN took me a day or two to get used to and now i never go back. Its faster and i have made very little typing errors. I got a 104 on my Circuit analyasis test thanks to this calculator. It was the highest grade in the class and the class avrege was 64. Ofcourse i studied a lot but without the calculator i would be trying to solve 3 variable linear complex number equations. And recently i found that this CAN DO LAPLACE TRANSFORMATIONS! the ti 89 CANNOT (theres plenty of software that allows it to do). And as an EE Laplace transforms will be a big part of my life. I hope this helped.

You can't go wrong buying either calculator. If you are lazy and don't want to do a lot of research finding how to work the HP 50g go for the ti 89. But if your wanting to get a little more of your calculator right off the box HP 50g might be the one for you.

Also the equation writer is very user friendly and makes plugging in long equations simple and easy to proofread.

 

[Phred101.2]

P.S. For the budding CS student: there's a HPGCC cross-devel. platform for the HP calcs, so you can write your own OS, or turn your HP50 into a web browser, or lab instrument, or whatever. Haven't looked at what the TI has available...

 

[bfr]

Ti has TIGCC and http://education.ti.com/educationportal/sites/US/productDetail/us_sdk_89_92p.html for C programming. There are also other languages to program (besides that built-in on-calculator programming languages) such as TI-Power and the Multi-Platform Langauge for Calculators, which also works on some Casio calculators as well. And then, there is of course assembly, which their are multiple assemblers for that are specifically designed for TI-calculator programming - TASM, SPASM, Brass, DASM, and OTBP Assembler (which is an on-calculator assembler, so you can program in assembly directly on your calculator without having to type in hex codes).

 

[shinny_head]

The Ti-89 may be easier to use at first. I have use HP calculators for years (1988)
I own 2 HP48SX, 1 HP48GX, 1 HP49G+ (a keyboard weenie), and I just ordered the
HP50G for my daughter. This calc is the keyboard fix for the 49G+.

Some schools and professors exclude the TI-89 use from tests.
My profs do not not know the POWER of the HP50.

The HP manual is not very good. But the google group comp.sys.hp48
and the www.hpcalc.org is the saving grace for calc. nubies
Many program available for download and best to use the SD ram card because
the computer connection is not easy to use.

You must struggle though the manual before asking questions.

The HP50 can work in ALG and RPN. I prefer RPN it is intuitive to the way I do math.

Programming is easy and the a much more powerful calculator.
BUT you must do some work to master it.
I found it worth the effort.
_________
Merry Christmas,

David

 

[56phil]

You've narrowed your list to two very good choices. Here is my take on your choice.

1. I have owned both. I still own the hp. I sold the ti to a physics teacher and she is very pleased with it.
2. Each has its strengths (e.g. the ti does implicit differentiation with less hassle than the hp; one the other hand, the hp has stronger statistical functions).
3. The hp is easier to program.
4. The hp has a steeper learning curve.
5. Once you know RPN you'll never want to use anything else on a calculator.

To sum things up, both are very good machines. I recommend the hp because of its greater flexibility.

Regards,

Phil