In fact if you write the original expression as sinh(x)/cosh(x) and then try
diff(%,x), trigsimp(%), you obtain 1/cosh^2(x). As Jaime said, Maxima can't
guess what you want.
-Alasdair
On 13 Feb 2007 07:00:02 -0000, Scott Ballantyne <sdb at ssr.com> wrote:
>
> Experimenting with maxima for the first time, I tried to compute the
> derivative of (%e^x-%e^(-x))/(%e^x+%e^(-x)), which I believe should
> be: 4/(e^x+e^-x)^2.
>
> Maxima gives 1 - (e^x-e^(-x))^2/(e^x+e^(-x))^2
>
> which is of course fine, but when I try to simplify this (I used
> ratsimp(%) and then factor(%)), maxima delivers
>
> 4e^(2x)/(e^(2x)+1)^2
>
> Perhaps this is correct, although it doesn't look like it at first
> blush.
>
> What is the best way to get the simple form of this expression?
>
> Thanks and many apologies if this is a common question.
>
> Scott
> --
> sdb at ssr.com
> "disce quasi semper victurus
> vive quasi cras moriturus"
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