RE: newbie PolarPlot question

*To*: mathgroup at smc.vnet.net*Subject*: [mg25054] RE: [mg25046] newbie PolarPlot question*From*: "David Park" <djmp at earthlink.net>*Date*: Thu, 7 Sep 2000 22:27:58 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Doug, It would be better to define your function this way... r[t_] := 16/(5 + 3 Cos[t]) Then PolarPlot[r[t], {t, 0, 2 Pi}] works fine. It isn't sufficient to put just r in the PolarPlot. You must have r[t]. You should probably read over again Section 1.7.1 on Defining Functions and Section 1.9.1 on Basic Plotting. As for copying input and output to a posting or email, it is not that important to have the In[] and Out[] cell labels. In fact, it is probably better not to have them because then it is easier to copy the statements back into a Mathematica notebook. If you convert any input or output cell to InputForm (use Shift-Ctrl-I) it will then copy into the posting as plain text which can be easily copied back into a notebook. The 2D formatted input can also be copied back to a Mathematica notebook and it will display immediately in StandardForm. However, it is not easy to read in the posting. David Park djmp at earthlink.net http://home.earthlink.net/~djmp/ > -----Original Message----- > From: Doug Magnoli [mailto:dmagnoli at home.com] To: mathgroup at smc.vnet.net > To: mathgroup at smc.vnet.net > Sent: Sunday, September 03, 2000 10:11 PM> Subject: [mg25054] [mg25046] newbie PolarPlot question > > > 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 > > > 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 >