Why Does My Calculator Show an Error with Tanh of a Complex Number?

[trustnoone]

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.

 

[jedishrfu]

I think your calculator manual says that the calculator doesn't support the complex number coefficient mode for hyperbolic sinh, cosh, tanh and other select functions.

http://www.google.com/url?sa=t&rct=...ttcjO3x9gBVXwPw&bvm=bv.69411363,d.cWc&cad=rja

 

[trustnoone]

I think your calculator manual says that the calculator doesn't support the complex number coefficient mode for hyperbolic sinh, cosh, tanh and other select functions.

http://www.google.com/url?sa=t&rct=...ttcjO3x9gBVXwPw&bvm=bv.69411363,d.cWc&cad=rja

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?

 

[jedishrfu]

Use google, in the search box enter tanh(5i) as an example and google calculator will show the answer - 3.38051501 i

 

[SteamKing]

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) = \frac{e^{z}-e^{-z}}{e^z+e^{-z}}

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

 

[trustnoone]

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) = \frac{e^{z}-e^{-z}}{e^z+e^{-z}}

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

Thanks mate, its actually on my formula sheet on my exam I got to take tomorrow, but if that's the case I really don't think I will be able to use it with only my calculator itself. Cheers though.

 

[jedishrfu]

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.