Re: problems plotting a derivative
- To: mathgroup at smc.vnet.net
- Subject: [mg54503] Re: problems plotting a derivative
- From: "Carl K. Woll" <carlw at u.washington.edu>
- Date: Tue, 22 Feb 2005 04:22:59 -0500 (EST)
- Organization: University of Washington
- References: <cvc80j$qqu$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
J.K.,
You were on the right track with Evaluate. The right way to use Evaluate is
to surround the problem argument with Evaluate, which in this case is the
first argument. So, try
ParametricPlot[ Evaluate[{D[f[x], x], x^2}] , {x, 0, 1}]
Carl Woll
"J. K. Smith" <rob at pi-overe.com> wrote in message
news:cvc80j$qqu$1 at smc.vnet.net...
> I've tried a lot of ways but nothing has worked so far.
> The following statements are my problem simplified:
>
> f[x_] := 2x^3;
> ParametricPlot[{D[f[x], x], x^2}, {x, 0, 1}]
>
> When I run this I get error messages griping about numbers not being
> valid variables but it doesn't end up plotting anything. In this example
> I should see a straight line.
>
> I've tried using Evaluate[ D[f[x],x] ] and lots of other schemes which
> seemed to work in the past but I can't get ParametricPlot to digest any
> of them. Something about the result of that derivative doesn't yield
> something that can be plotted. But I don't know what property it is.
>
> Would you kind Mathematica gurus please get me thru this one (too)?
>
> Thanks.
>
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