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How to Tanh(complex number)

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  1. Jun 23, 2014 #1
    As the title shows, I want to do they hyperbolic tan of a complex number, using my calculator (casio fx100ms) but I keep getting a maths error, whether I do it using the tanh function or if I try the

    (1-e^(-2x))/(1+e^(-2x))


    Any help would be awesome. Thanks.
     
  2. jcsd
  3. Jun 23, 2014 #2

    jedishrfu

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  4. Jun 23, 2014 #3
    Nooooo :(, thanks for looking into it mate, I thought it was just something I was doing wrong. Is there any way I can do it normally? like any way I can do it say like the hard way?
     
  5. Jun 23, 2014 #4

    jedishrfu

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    Use google, in the search box enter tanh(5i) as an example and google calculator will show the answer - 3.38051501 i
     
  6. Jun 23, 2014 #5

    SteamKing

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    Dang calculators only support real numbers! (Well, most of 'em anyways)

    Tanh(z) can be evaluated by using the definition of the tanh function with complex argument z,

    tanh(z) = sinh(z) / cosh(z) = [itex]\frac{e^{z}-e^{-z}}{e^z+e^{-z}}[/itex]

    which is not as easy to calculate as it looks. See:

    http://www.uni-graz.at/imawww/vqm/pages/complex/12_tanh.html

    You can always use Wolfram Alpha to calculate a tanh(z) for a specific value of z
     
  7. Jun 23, 2014 #6
    Thanks mate, its actually on my formula sheet on my exam I got to take tomorrow, but if thats the case I really don't think I will be able to use it with only my calculator itself. Cheers though.
     
  8. Jun 23, 2014 #7

    jedishrfu

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    Perhaps you should ask your teacher about it before the exam. You might need a better calculator TI-83 ??? but not sure if it has the same limit or not.

    CORRECTION:

    http://tibasicdev.wikidot.com/tanh

    TI caclculator doesn't support complex numbers with tanh either.
     
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