Re: problems plotting a derivative

*To*: mathgroup at smc.vnet.net*Subject*: [mg54555] Re: problems plotting a derivative*From*: sherifffruitfly at gmail.com*Date*: Tue, 22 Feb 2005 04:26:03 -0500 (EST)*References*: <cvc80j$qqu$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

J. K. Smith wrote: > 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. Using f'[x] in the intuitive fashion works. That's the only 100% intuitive way I know how to do the trick...