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Seeking calculator suggestions for solving linear equations with complex coefficients

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

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  1. Steven O.

    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. 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.

    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
    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.
    http://www.SpyingOnTheCollegeOfYourChoice.com
     
  4. Eric Gisse

    Eric Gisse Guest

    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 Webb

    Peter Webb Guest

    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
    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
     
  6. Wayne Brown

    Wayne Brown Guest

    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.
     
  7. redbelly

    redbelly Guest

    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.

    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 who

    Guess who Guest

    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 Phantom

    The Phantom Guest

    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*.
     
  11. The Phantom

    The Phantom Guest

    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. Justin

    Justin Guest

    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. w2aew

    w2aew Guest

    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 who

    Guess who Guest

    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
    fall flat on your face.
     
  15. Jim Spriggs

    Jim Spriggs Guest

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

    k wallace Guest

    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
     
  17. k wallace

    k wallace Guest


    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 Spriggs

    Jim Spriggs Guest

    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 cohen

    martin cohen Guest

    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. JANA

    JANA Guest

    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
     
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