newbie PolarPlot question

*To*: mathgroup at smc.vnet.net*Subject*: [mg25046] newbie PolarPlot question*From*: Doug Magnoli <dmagnoli at home.com>*Date*: Sun, 3 Sep 2000 22:11:05 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

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. ....and, BTW, how do you get all those quotes from mathematica pages into this newsgroup without having to edit? I tried to copy, e.g., In[32]:= PolarPlot[4, {t, 0, 2 Pi}] and I don't get the In[32]:= part. Also, when copying those error messages, I had to edit extensively, or else they look like this when copied / pasted: ParametricPlot::"pptr": "\!\({\(\(r\\ \(\(Cos[t]\)\)\)\), \(\(r\\ \ \(\(Sin[t]\)\)\)\)}\) does not evaluate to a pair of real numbers at \!\(t\) \ = \!\(2.617993877991494`*^-7\)." tia, -Doug Magnoli