Seeking calculator suggestions for solving linear equations with complex coefficients

I am returning to school, adult ed kind of thing, to learn about electronics. For the tests, I need a calculator which can solve systems of linear equations with complex coefficients. (When doing the homework at home, I use Mathcad.)

I just went to Radio Shack, and got a case of sticker shock (much like what I'm feeling these days when I go to buy gasoline for my car). The cheap calculators, which cannot do systems of linear equations, cost around $20. The calculators which look like they probably can do systems of linear equations -- although it's not entirely clear from the packaging -- jump to around $125 to $150. Prices on E-bay are cheaper, but I'm not entirely sure what I am buying.

Can someone suggest a few models of calculators that:

1. Can solve systems of linear equations with complex coefficients.
2. Are relatively easy to learn to use, and to do the data entry.
3. If possible, perhaps cost less than 0, though I will spend 0+ if it's unavoidable.
4. Does other stuff that is like to come up in undergrad level EE courses and tests.

If anyone really wants to be a Saint, take a peek on E-bay, at some of the stuff currently on sale, and tell me if any of those calculators would meet my requirements. (Here's a list of just a few that are currently being offered under the keywords "Calculator" and "Scientific": TI-81, TI-83, TI-85, TI-89.)

A check of the TI Web site suggests that the TI-83 or TI-84 have the features I want, but again, it's hard to know without having used them. At the high end, they have the Voyager 200 (which costs $200), and the TI-89 Titanium (which costs $150). Recommendations for the minimum I really need for my purposes -- and for options for brands other than TI -- would be appreciated.

Thanks in advance for all replies.

Steve O.

"Spying On The College Of Your Choice" -- How to pick the college that is the Best Match for a high school student's needs.

To be filed under: If you can't offer a useful, on topic reply, why do you bother posting at all? Thanks so much, pal.

Anyone else, with a *constructive reply*, not to mention a non-judgmental, non-snobby reply?

Steve O.

"Spying On The College Of Your Choice" -- How to pick the college that is the Best Match for a high school student's needs.

With all respect, I don't think I understand why you absolutely positively need a calculator that can solve systems of linear equations with complex coefficients.

Yes, I do realize that problems of that sort appear in electronics, but that is really just a small part of it.

My personal experience (I have an M.Sc. in electrical engineering) is that solving linear equations is not a big deal.

During highschool I had a basic Casio calculator, with support for numerical integration. During my engineering studies I found I had to upgrade, but not because of linear equations. Rather, I needed hyperbolic functions of complex arguments and that was just a pain using my old calculator. So I upgraded to HP 32, which I still have today. I've never needed anything else.

I'm convinced that the time it takes to enter a system of linear equations (and making sure you've typed correctly) is better spent solving the linear system by hand.

-Michael.

What do the other students in your class use? What can the professor suggest or recommend?

Like others, I'm surprised that such a calculator is required. But if that is how your professor is running things, s/he must have an idea of what is available.

Mark

He gave you some sound advice. If you have the intelligence to complete the course that he did and then put to practice for some years, you'd heed that advice, ...especially the "understanding" part.

Good luck.

I'm a second year mechanical engineering grad student right now, and while it seems I don't use my calculator ( TI-83 ) as much as in undergrad it is still useful. It seems a lot of my friends however liked the TI-89 better for its ability to enter and solve equations as you want. Also, other things I've heard is that CASIO is harder to learn to use. Don't know anything about the HP's.

That being said, I'ld like to hear when some of these people graduated. I had one friend that used this old beat up graphing calculator, but refused to get a new one for some of the same reasons as some of you. I think he almost quoted Eric Gisse with: "Doing it on the calculator means slaving yourself to technology"

I'm just guessing that those who have shunned Steve O are older people who graduated pre-graphing calculator. (or could be recently and in your profession one just isn't needed). One trend in courses since the advent of the calculator is that the work load increased greatly. I'ld say it would be almost impossible now to go to college without the aid of a calculator.

i.e. the washing machine did not decrease the amount of time that traditional women spent cleaning, it increased the amount of cleaning done in a day.

Because, as he said, he will be required to do so on tests.

Oftentimes, the kind of problems one must solve in course work are rarely encountered after graduation, but the course work is still required to graduate.

Solving a linear system (of order > 2) involves a lot of arithmetic. How would you do the arithmetic? By hand? With log tables? Or with a calculator? If you use a calculator, you will still have to enter the numbers (and make sure you've typed correctly), and if it's a system with order > 2, you would probably have to enter some numbers more than once during the reduction; you would have to write down intermediate results, and later re-enter them. And the OP will have to do *complex* arithmetic, which greatly increases the work and chance of error during all the writing down of intermediate results and later re-typing them in. If the calculator can solve a linear system, then he will only have to correctly enter the (complex, in his case) coefficients *once*.

Hewlett-Packard has made calculators that do complex arithmetic since the HP15C was introduced. But don't try to get one of those; they're collectors items and go for quite high prices on eBay!

The HP48SX or HP48GX will meet your needs and can be had on eBay for well under $100. I would recommend the HP48GX; it's a little more powerful than the SX, but both will solve linear systems with complex coefficients.

Best Match for a high school student's needs.

Since the HP-15C and HP32SII are not sold new anymore, and fetch amazing prices on eBay - a decent new alternative from HP is the new HP33S. It is basically an upgrade of the HP32SII, and costs about $50 new.

Get what you need without thought to cost. You need it, then pay for it as part of the course requirement. Either TI or HP will meet those needs. Ask your prof to suggest one. If he is reluctant to give you a definite reply, then there's something terribly wrong with the course you are taking.

The following is from a distance-ed site, and possibly worth a look as to expectations. High school students [here. at least]solve problems in systems of equations and matrix algebra. It is, and should be an expected capability of an engineering student. It gets a LOT more complicated than this.

This is not being mean-spirited: You should check with your prof to see what are the expectations during an exam. If you are allowed to use a calculator, then you should be using it at home, of course. If not, then you should not be worried about the cost; it's part of geting a worthwhile education. If not allowed, then you definitely need to practice to gain the skill needed to do it in a timely manner during an exam. I've heard it many times, "I didn't have enough time.", from those who hadn't practiced and mastered the necessary skills as they should. Be sure you know the requirements, or you can fall flat on your face.

I'm partial to TI's, having used them all through school. I wouldn't bother with the V-200, way more than you need and a pain in the ass to enter data. The TI83 plus is my personal favorite- systems of equations are easily solved in matrix form. However, if you're doing a lot of solving systems with complex coefficients, go with the TI 89. In it, you can enter 'i' directly into the matrix without first doing Eulerian conversions to terms with sin and cos, which IIRC, you have to do to use the complex terms in matrix form solving of complex equations on the TI 83 and 83 plus. One other really nice thing that the 89 does is symbolic integration. True, once you have calculus under your belt, the integrals you need to solve are rarely all that difficult to do by hand, and when learning calculus, don't use a calculator! But it's a good option to have, too. The 3D graphical feature on the 89 is overrated, I think- I used it once in a vector calculus class and only to play with after that. another thing that *I* liked about the TI 89- it has a program you can put on it so it functions as a pretty complete PDA- schedule, contacts, etc- one less gadget to carry- but I"m gadget happy anyway.

enjoy- I saw a TI 89 go on Ebay for $41 the other day- WELL worth it! k wallace

Best Match for a high school student's needs.

if this is what you need, get the TI 89. The 83's process for doing this is way slower and involves more steps, so more places to screw it up. The 89 happily allows you to enter complex values in a matrix, where the

83 family does not do it as willingly. Look on Ebay, I just saw an 89 go for around $40. Cheap for what it is. k wallace

Best Match for a high school student's needs.

So I guess when you said "Thanks in advance for all replies" you didn't really mean it, eh?

His reply *was* useful, on topic, and constructive, not to mention polite, which yours certainly was not. Your inability to appreciate his advice does not make it any less valuable.

--
Wayne Brown  (HPCC #1104)  | "When your tail\'s in a crack, you improvise
fwbrown@bellsouth.net      |  if you\'re good enough.  Otherwise you give
                           |  your pelt to the trapper."
"e^(i*pi) = -1"  -- Euler  |           -- John Myers Myers, "Silverlock"

The class is a distance learning class, i.e., off-campus, learn from home. There is no contact with other students, so I have no idea what they use. The professor, unfortunately, offers only relatively brief, terse replies to e-mails. That is why I am posting here.

As for using a calculator -- I do need to visit the campus three or four times to take tests. For problems involving mesh and node analysis of circuits, the problems will involve systems of linear equations with two or three variables, and if capacitors or inductors are involved, the coefficients will be complex. Such equations cannot be solved, reliably and by hand, in the time available to take a test

-- at least not by me, using standard matrix methods. This is why I am seeking a reasonable calculator solution.

Again, any on-topic answers -- meaning, just tell me which affordable calculators will do the trick -- would be appreciated.

Steve O.

"Spying On The College Of Your Choice" -- How to pick the college that is the Best Match for a high school student's needs.

The problem is that the 33s does not solve linear equations.

I would recommend the HP 49G+, which can solve complex linear systems of arbitrary size. The TI 89 would probably also be ok.

Martin Cohen

Whoa, whoa, whoa. Who knows what the op's financial situation is?

--
I don\'t know who you are Sir, or where you come from, 
but you\'ve done me a power of good.

Then ask questions that can be replied to tersely. Such as:

Do I need a calculator in order to get a good grade?

If "yes", what calculator do you recommend?

If the recommendation is for an expensive calculator, tell the course administrators that they are morally obliged to indicate in the course description (or whatever it is that possible future students see before they actually sign up for the course) that an expensive calculator is required.

--
I don\'t know who you are Sir, or where you come from, 
but you\'ve done me a power of good.

Back in the late 60's when I was in engineering school, we used slide rules with a book for the tables lookup. We did everything manually. There was no such thing as a hand held calculator like today. Computers took up a large room, were complex to program and operate, and were expensive to use.

If you want a great calculator, look at the TI Voyager 200. This one is expensive, but it is the best calculator I ever used. The TI - 89 is also excellent. I like the 200 because of the full alpha-numeric keypad, which makes it a lot easier to use.

Since I would guess you are interested in seriously taking up your studies, it would be wise to treat yourself to the best possible.

--

JANA _____

I just went to Radio Shack, and got a case of sticker shock (much like what I'm feeling these days when I go to buy gasoline for my car). The cheap calculators, which cannot do systems of linear equations, cost around $20. The calculators which look like they probably can do systems of linear equations -- although it's not entirely clear from the packaging -- jump to around $125 to $150. Prices on E-bay are cheaper, but I'm not entirely sure what I am buying.

Can someone suggest a few models of calculators that:

1. Can solve systems of linear equations with complex coefficients.
2. Are relatively easy to learn to use, and to do the data entry.
3. If possible, perhaps cost less than 0, though I will spend 0+ if it's unavoidable.
4. Does other stuff that is like to come up in undergrad level EE courses and tests.

If anyone really wants to be a Saint, take a peek on E-bay, at some of the stuff currently on sale, and tell me if any of those calculators would meet my requirements. (Here's a list of just a few that are currently being offered under the keywords "Calculator" and "Scientific": TI-81, TI-83, TI-85, TI-89.)

A check of the TI Web site suggests that the TI-83 or TI-84 have the features I want, but again, it's hard to know without having used them. At the high end, they have the Voyager 200 (which costs $200), and the TI-89 Titanium (which costs $150). Recommendations for the minimum I really need for my purposes -- and for options for brands other than TI -- would be appreciated.

Thanks in advance for all replies.

Steve O.

"Spying On The College Of Your Choice" -- How to pick the college that is the Best Match for a high school student's needs.

I thought his reply was useful and on-topic. He has an MSc in the subject you are studying, and identified that you probably won't need the functionality that you ask about. He gave useful hints on what you might actually need in a calculator (support for hyperbolic functions with complex arguments) and suggested an inexpensive unit which will do what you actually need. He was not judgemental, he was not "snobby"; he struck me as knowledgable, helpful, and pleasant.

You, on the other hand, strike me as a rude and stupid person. Your reply was completely unwarranted. If you go back to school, then with luck you will meet lots of people with Masters degrees tryting to tell you what you need to know to be an EE. Treat them like you treated Mr Jorgensen and nobody will bother talking to you, and you will fail.

Here's my useful, on-topic reply: don't bother with the calculator at all, you won't need it flipping burgers. And with your attitude, you may not even get to do that.

Hope this helps

Peter Webb