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Re: PolarPlot

  • To: mathgroup at
  • Subject: [mg87678] Re: PolarPlot
  • From: Helen Read <hpr at>
  • Date: Tue, 15 Apr 2008 05:54:28 -0400 (EDT)
  • References: <ftmu5p$50d$> <ftv938$80f$>
  • Reply-to: HPR <read at>

dh wrote:
> Hi Bruce,
> the radius in polar coordinates has to be real and positive. Therefore, 

Actually, no. In polar coordinates r is a *directed* distance, which may 
be positive or negative.

> r=Sqrt[Cos[phi]] can not be the correct formula, we would get imaginary 
> values. To prevent this, we may e.g. write: r=Sqrt[Abs[Cos[phi]] what 
> gives the plot you are looking for.
> hope this helps, Daniel

Helen Read
University of Vermont

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