Re: How to plot derivative directly?
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- Subject: [mg130259] Re: How to plot derivative directly?
- From: papushaan at gmail.com
- Date: Sat, 30 Mar 2013 04:07:56 -0400 (EDT)
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> Dear mathgroup,
>
> it seems to me, that response to my question shall be very simple,
> but I cannot find it. :-(
>
> I want to plot the derivative of the function. I would like to do it
> directly, something like:
>
> Plot[D[x^3 - 6 (x + 1)^2 + x - 7, x],{x,-3,8}]
>
> It returns: General::ivar: "-2.99978 is not a valid variable."
>
> I can understand that it is because local variable x from Plot command
> interferes with the x variable from the D[].
>
> Yes I can bypass the problem by:
> deriv = D[x^3 - 6 (x + 1)^2 + x - 7, x]
> Plot[deriv, {x, -3, 8}]
>
> which is fully functional, but as far as I know Mathematica, there must
> be some simple solution how to do it directly inside the Plot[].
>
> Thanks in advance for kick-off
>
> Jakub
Jakub,
Just use a very simple command
Plot[Evaluate[D[x^3-6 (x+1)^2+x-7,x]],{x,-3,8}]
Chair