# Seeking calculator suggestions for solving linear equations with complex coefficients

Discussion in 'Electronic Basics' started by Steven O., Sep 8, 2005.

1. ### Steven O.Guest

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 \$100, though I will spend
\$100+ 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.
http://www.SpyingOnTheCollegeOfYourChoice.com

2. ### Michael JørgensenGuest

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.

3. ### Steven O.Guest

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

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.
http://www.SpyingOnTheCollegeOfYourChoice.com

4. ### Eric GisseGuest

If it is big enough to NEED computational aid, use MATLAB. Otherwise,
Gauss-Jordan reduction. Anything short of a palmtop with MATLAB on it
will be a pain in the ass to enter data into. The TI-83 does support
what you want, but it is a bitch to enter the data.

Learn it now, or learn it later. You will see linear algebra one of
these days anyway. Doing it on the calculator means slaving yourself to
technology without understanding the base mathematics behind what you
are doing. If that is your wish, buy a TI-83 - they are what, 50 bucks?
Or better yet, buy a damn linear algebra book and reduce those linear
equations to their solutions faster than it takes to enter them into
the calculator.

Oops. I left a little snob in there, and I think i was a bit
judgemental.

5. ### Peter WebbGuest

Yes, I do realize that problems of that sort appear in electronics, but
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

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

6. ### Wayne BrownGuest

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,
does not make it any less valuable.

7. ### redbellyGuest

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

8. ### Steven O.Guest

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.
http://www.SpyingOnTheCollegeOfYourChoice.com

9. ### Guess whoGuest

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.

10. ### The PhantomGuest

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
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*.

11. ### The PhantomGuest

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.

12. ### JustinGuest

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. <-- a comment from a technology and society elective

13. ### w2aewGuest

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.

14. ### Guess whoGuest

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.

http://distance-ed.math.tamu.edu/Math640/chapter1/node5.html

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

15. ### Jim SpriggsGuest

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

16. ### k wallaceGuest

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,

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

17. ### k wallaceGuest

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

18. ### Jim SpriggsGuest

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.

19. ### martin cohenGuest

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

20. ### JANAGuest

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 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 \$100, though I will spend
\$100+ 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.
http://www.SpyingOnTheCollegeOfYourChoice.com