problems plotting a derivative

*To*: mathgroup at smc.vnet.net*Subject*: [mg54479] problems plotting a derivative*From*: "J. K. Smith" <rob at pi-overe.com>*Date*: Mon, 21 Feb 2005 03:44:47 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

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. remove the dash if emailing

**Follow-Ups**:**Re: problems plotting a derivative***From:*DrBob <drbob@bigfoot.com>

**Re: problems plotting a derivative***From:*Chris Chiasson <chris.chiasson@gmail.com>

**Re: problems plotting a derivative***From:*yehuda ben-shimol <bsyehuda@gmail.com>