Re: newbie PolarPlot question

*To*: mathgroup at smc.vnet.net*Subject*: [mg25070] Re: [mg25046] newbie PolarPlot question*From*: BobHanlon at aol.com*Date*: Thu, 7 Sep 2000 22:28:13 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

In a message dated 9/3/2000 10:22:37 PM, dmagnoli at home.com writes: >I've defined: > >r[t] := 16/(5 + 3 Cos[t]) > >Then I load Graphics, with: > ><<Graphics` > >and ask for: > >PolarPlot[r, {t, 0, 2 Pi}], which tells me: > >ParametricPlot::pptr: >{r Cos[t], r Sin[t]} does not evaluate to a pair >of real numbers at t = 2.617993877991494`*^-7 > >ParametricPlot::pptr: >{r Cos[t], r Sin[t]} does not evaluate to a pair >of real numbers at t = 0.25488992540742256`. > >ParametricPlot::pptr: >{r Cos[t], r Sin[t]} does not evaluate to a pair >of real numbers at t = 0.5328694051959509`. > >General::stop: >Further output of ParametricPlot ::pptr will be >suppressed during this calculation. > >Near as I can make out, x and y should both evaluate to real numbers for >any value of theta between 0 and 2 Pi, so I don't know what I'm doing >wrong. > Needs["Graphics`Graphics`"]; The function definition should read: r[t_] := 16/(5 + 3 Cos[t]); The plot call should read: PolarPlot[r[t], {t, 0, 2 Pi}]; Bob Hanlon