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Seeking calculator suggestions for solving linear equations with complex coefficients

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Mike Berger

Jan 1, 1970
0
You people sure are judgemental.

If you've been out of school for more than 3-4 years, you
might be surprised at how things change. It is not unusual
for courses to require that work be done with a calculator
(and tests may be based on the premise that every single
student has one with the necessary capabilities). That
doesn't obviate learning the theory behind the math. I have
no doubt that some of you dinosaurs used charcoal to derive
all advanced formulas from basic premises on the back of your
shovel, but classes are not taught that way anymore.
 
N

Nelson Johnsrud

Jan 1, 1970
0
The said:
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*.
I had a TI-60 and a TI-68 years back that would do this. These were
about $30 calculators, as I recall, and I don't think they are available
anymore. At least I haven't seen them in a long time. (Maybe eBay?) I
used the linear solving capability a few times just to play with it (new
toy), but I really never used it much in actual practice. It just
seemed easier for me to keep track of everything by putting it on paper.
Easier error checking too. That's just me and personal preferences
though. I'm sure with practice it would be a quick solve on the calculator.

Nels
 
D

Dave Rusin

Jan 1, 1970
0
You people sure are judgemental.

...., he said judgementally.
If you've been out of school for more than 3-4 years, you
might be surprised at how things change. [...about calculators...]
but classes are not taught that way anymore.

Those of us who actually teach might disagree.

I have yet to see a calculator that can help with a problem
like, "Prove that R[x] is a vector space over R."

dave
 
V

Vincent Johns

Jan 1, 1970
0
JANA said:
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.

Tee-hee... I'm afraid you mean "... best possible within the
constraints of the testing situation." :-(

My choice for "best possible" outside of that would be a high-powered
notebook PC with a good CAS on it, such as Maple or Mathematica or
MathCAD. It would also come with a full alpha-numeric keyboard, no
extra charge. But it would probably be frowned upon during tests.
(Darn.) However, for solving problems (both real-world and imaginary),
these would have immense potential, well worth the (somewhat massive)
time & effort needed to learn to use them.

-- Vincent Johns <[email protected]>
Please feel free to quote anything I say here.
 
K

Kitchen Man

Jan 1, 1970
0
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?

I suppose that was really snobby of Michael to say, "With all
respect." What did you want, somebody to come up and say, "Hey fella,
I found that calculator you need for $19.95 at Wal-Mart, and I can
bring beer and pizza over tonight and teach you to use it?" You got a
very good response outlining an opinion that you probably don't need
an expensive calculator to do lengthy linear equations, and you
responded like a complete ass.

For the record, I like an HP-15C, but even then, I didn't really need
it until I was required to do successive approximation problems. It
has programming functionality which is what it sounds like you will
need, and this should be available in a less expensive calculator. It
also has reverse Polish notation, which is very handy for complex
equations. Do you know RPN? If you really want a specific
recommendation, you should ask your instructor.

About Michael's comment on entering the system of equations, you are
probably going to have to do that pre-test, pre-class, when
programming the calculator, provided you are given the form of the
equations to be encountered prior to testing. If you don't have
pre-made forms, then it's just as he says; it might be as easy to do
it by hand.

Now, apologize to Michael, you lout. And no, I didn't smile when I
said that.
 
V

Virgil

Jan 1, 1970
0
[/QUOTE]

There are a variety of Hewitt-Packard callculators that will solve
systems of linear equations with complex cefficients.

The HP 49 series, for example will solve them either in equation form or
matrix-vector form or augmented matrix form (by matrixrow reduction),
and in exact or approximate form.
 
M

Michael A. Terrell

Jan 1, 1970
0
Mike said:
You people sure are judgemental.

If you've been out of school for more than 3-4 years, you
might be surprised at how things change. It is not unusual
for courses to require that work be done with a calculator
(and tests may be based on the premise that every single
student has one with the necessary capabilities). That
doesn't obviate learning the theory behind the math. I have
no doubt that some of you dinosaurs used charcoal to derive
all advanced formulas from basic premises on the back of your
shovel, but classes are not taught that way anymore.


If a calculator is required for the course there should be a
specified model, or models and this information should be available from
the school. If not, I would question the quality of the school. If the
instructor is incapable of setting proper specifications, he isn't much
of a teacher.
 
J

Jim Spriggs

Jan 1, 1970
0
Mike said:
(and tests may be based on the premise that every single
student has one with the necessary capabilities). ...

I've got nothing against people using calculators to do error-prone
arithmetic, but I would make two points:

(1) Solving systems of linear equations with complex coefficients has
got nothing to do with calculators.

(2) If a test is a test of whether one has the appropriate calculator or
not, it should be called that and shouldn't affect in any way affect
ones grade in electronics.
 
G

Guess who

Jan 1, 1970
0
You people sure are judgemental.
I have
no doubt that some of you dinosaurs used charcoal to derive
all advanced formulas from basic premises on the back of your
shovel

That makes sense ...the source of reply, not the rightness of it. You
must be far removed from reality. The calculator is a tool to be used
on occasion. There are other tools thatr serve as well and beter in
some circumstances. The myths surrounding the need for calculator and
computer are being demolished daily. One of the best compliments I
experienced was from a class where neither were used [although I have
taught the use of both.] A year later, one student thanked me with,
"We are teaching the other kids how to do their trig." You have no
idea of what you speak.
 
N

Nanu5871

Jan 1, 1970
0
Steven said:
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


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For electronics (associate degree level) we just use a TI-36X solar.
It does Log/anti-log for dB calculations, ENGineering units, fractions,
sin/cos/tan,etc. I also bought a TI-84+ which as they said is a bugger
to enter in complex problems and you would need to study the manual for
it over Xmas break to understand it.
I recommend a notebook with Matlab or MuPad(free) if the instructor lets
you but ask first if it is permitted on the tests.
TI-36X is best for doing 98% of all the problems you will see.
Nanu5871
 
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Nanu5871

Jan 1, 1970
0
Guess said:
You people sure are judgemental.

I have
no doubt that some of you dinosaurs used charcoal to derive
all advanced formulas from basic premises on the back of your
shovel


That makes sense ...the source of reply, not the rightness of it. You
must be far removed from reality. The calculator is a tool to be used
on occasion. There are other tools thatr serve as well and beter in
some circumstances. The myths surrounding the need for calculator and
computer are being demolished daily. One of the best compliments I
experienced was from a class where neither were used [although I have
taught the use of both.] A year later, one student thanked me with,
"We are teaching the other kids how to do their trig." You have no
idea of what you speak.



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http://www.avast.com
I think you will find that for the most part, TI-36X will do nice for
calculations and MultiSim 7,8, or comparable will be best for the rest
of the electronics stuff.
I have never seen any electronics tech or engineer bother with using the
TI-84,89,etc or other overpowered calculator. They always use a simple
engineering calculator and simulation software.
Save money, headaches, and stress....but if you insist, I would be glad
to sell my TI-84+ silver edition for $129 to you...if you just gotta
have the overpowered calculator in your hands.
Nanu5871
 
K

k wallace

Jan 1, 1970
0
Jim said:
Mike Berger wrote:




I've got nothing against people using calculators to do error-prone
arithmetic, but I would make two points:

(1) Solving systems of linear equations with complex coefficients has
got nothing to do with calculators.

No, it doesn't. But learning the means, methods, why's and wherefores
does NOT mean that they are quick and easy to do by hand,accurately,
under testing conditions.

Therefore, (Though I'm sure I wont' change the mind of a single
instructor),
either- give *purely theoretical* tests- no numbers at all.
or- give *few enough* problems that the students will for sure have no
trouble doing the math by hand. And, along those lines, since it is an
artificially induced situation, make the numbers ones that don't turn
into crazy huge-denominator fractions, etc.
Instructors want to test for understanding, not calculating ability, right?
That's why I think all-theoretical tests are the way to go. My
engineering professors thru college often did that, and it sure didnt'
make the tests easier.

you do have to know how to set up and solve a complex-coefficient matrix
in order to even enter it into the calculator.
If you want the students to prove that they can do complex-coefficient
math by hand, that's another test entirely.

my 0.02,
k wallace
 
K

k wallace

Jan 1, 1970
0
Guess said:
I think you might be missing the point. Fractions are taught using
the simplest of values, so children can grasp the concept.

<snip good points>

that's exactly what my next point was, did you read it?

To use numbers that work out 'well' in the complex coefficient matrix,
OR give few enough problems that you know they can be solved in the time
alloted - since the point is not to test arithmetic skills, but
understanding of the electronic circuits (which is where this all
started, and where, with inductors IIRC, you have to know how/when to
use them).

I don't know how many tests I took in college where I understood the
material just fine, but there was SO much to do on the test that i was
scrambling to finish in the time alloted. And I'm a med-to-fast worker.

k wallace
 
G

Guess who

Jan 1, 1970
0
No, it doesn't. But learning the means, methods, why's and wherefores
does NOT mean that they are quick and easy to do by hand,accurately,
under testing conditions.

Therefore, (Though I'm sure I wont' change the mind of a single
instructor),
either- give *purely theoretical* tests- no numbers at all.

I think you might be missing the point. Fractions are taught using
the simplest of values, so children can grasp the concept. You can
use simple values without getting into some generalised algebraic
form. The concept does not change when the values become more
complicated [for them], but that does not validate teaching fractions
using 177ths and so using a calculator that does fractions. What one
does do is to use halves, quarters, thirds, fifths ....common smaller
values and their multiples. Once the concept i learned *then* ny
values will do. *Then* the concept can be generalised into algebraic
form. So it was that geometry and trig was taught using simple
radical values [and so the need to learn that arithmetic as well.]
What could be simpler than the symbolic representation of sqrt(3) and
sqrt(5)? It is still introduced using the simplest of values. The
two triangles found in the geometry set still used in schools are
sufficient to give a large enough sample of values to study
trignometry on the whole. Using other values again does not validate
the use of the calculator from the start.

Yes, the calculator should be used when the study develops into more
"realistic" situations, but that comes next, not first, and to learn a
concept, it is *best* to use simple values at first without any effort
to learn something new at the same time. In the study of trig, for
example, the study can be extrapolated *after* learning the basic
concepts, using finer accuracy in measurement and calculation of
angles, and so using the calculator to advantage.
 
K

Kaimbridge

Jan 1, 1970
0
Steven said:
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.

I just picked up the Sharp EL-506VB on sale at Circuit City for $6.99
(Reg. $19.99):


http://64.233.161.104/search?q=cach...ilReview.do+Sharp+EL-506VB+circuit+city&hl=en


http://www.digitaladvisor.com/gadge...in-powered-scientific-calculator_reviews.html


http://www.amazon.com/gp/product/customer-reviews/B00005BHPR/103-3968973-7083857

I was mainly looking for just a simple "checkbook calculator" (and
maybe for some whim-of-the-moment equation I may have churning in my
head and I'm away from the 'puter! P=)--but at that price...

~Kaimbridge~
 
G

Guess who

Jan 1, 1970
0
I don't know how many tests I took in college where I understood the
material just fine, but there was SO much to do on the test that i was
scrambling to finish in the time alloted. And I'm a med-to-fast worker.

Perhaps we can agree to disagree on this a little, since there are
valid arguments either way. Perhaps we agree that there is a use, but
overuse is a considerable problem in junior and high school at least.
I can certainly see the validity in college and university, but even
there it is not something that must be worn constantly. There are
problems of a type and nature that can be readily solved without.

Consider a simpler true case study: In high school, after much effort
the student understood that to change from mm to cm he had to divide
by ten. He *would not* let go of his calculator.

Anothr: The girl [family friends] who was in a pink fit, saying she
"hated" geonetry ...just a few days befor her exam. She had gone
through the study using Geometer's Sketchpad, a very useful tool.
Tutoring her so that she could say, "Is that all there is to it?" took
two hours and the old geometry set.

I can't speak for what you might have have to do, but although I saw
others struggling mightily through an exam, I have on occasion
finished the same exam with time enough to go over the results and
then have still ample time to spare. One factor is relative
preparedness, a factor I've seen as a teacher watching the efforts of
many students over the years. We can be our own worst enemy at times.
It can happen in the pressure of an exam, as the question becomes
clear or not before answering. That is not to say that occasionally
an exam can not be prepared thoughtlessly. It does say that it might
also be a matter of perspective. Even with the calculator, I've seen
those competent enough, but still not skilled enough to use it
readily, and every effort is time-consuming. As with the study on
hand itself, there needs to be sometimes inordinate time and effort
spent in practice, and the tool can for some get in the way, rather
than be an advantage. Again, it's a matter of perspective and
relative ease of use.

....just one perspective. It's still a matter of the OP talking to the
prof and getting the reply he wants ...do you need the claculator for
the exam.
 
M

Mike Berger

Jan 1, 1970
0
How is it any different than the expensive textbooks that are
often required?
 
K

k wallace

Jan 1, 1970
0
Guess said:
Perhaps we can agree to disagree on this a little, since there are
valid arguments either way. Perhaps we agree that there is a use, but
overuse is a considerable problem in junior and high school at least.
I can certainly see the validity in college and university, but even
there it is not something that must be worn constantly. There are
problems of a type and nature that can be readily solved without.

I absolutely agree with the above. Overuse (and use when *thinking*
would be a better tool) holds kids in HS back from learning concepts,
finding those 'shortcuts' that we do in our heads (all the trig
root-two, root-three stuff I'm thinking of now) that lead to a complete
and connected understanding.

regards,
k wallace
 
K

Kitchen Man

Jan 1, 1970
0
How is it any different than the expensive textbooks that are
often required?

Easy. The calculator is still useful after you graduate. :)
 
V

Vincent Johns

Jan 1, 1970
0
Kitchen said:
Easy. The calculator is still useful after you graduate. :)

I have occasionally bought a textbook that had lasting value. And with
all the work involved in understanding the contents, I hate to get rid
of them. I even, a couple of months ago, came across one of my father's
old textbooks, a book of mathematical tables (base-10 logarithms, etc.),
plus some interesting formulas. Not too useful now, perhaps, but
interesting.

Now I'm starting to see *vanishing* textbooks. I recently downloaded
some beta-version software (fortunately free of charge) from Microsoft,
but after a while of reading the documentation bumped up against a
message to the effect that that version had expired and I had to get a
new version (again free of charge). It's a way to try to ensure that I
don't spend lots of time reading out-of-date stuff, but having to update
frequently could be a bit of a nuisance. Students can often buy (at
cheap prices) computer software that expires at the end of the semester.
That's an extra incentive to finish all the projects on time, since
you know the tools will disappear! Calculators probably have basic
enough functions that it's not too important to stay up to the minute
with them.

-- Vincent Johns <[email protected]>
Please feel free to quote anything I say here.
 
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