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Re: PolarPlot

  • To: mathgroup at
  • Subject: [mg87775] Re: PolarPlot
  • From: dh <dh at>
  • Date: Wed, 16 Apr 2008 22:31:45 -0400 (EDT)
  • References: <ftmu5p$50d$> <ftv938$80f$> <fu1u66$oom$>

Hi Helen,

just saw your reply. A coordinate system as you propose would assign 

more than one coordinate tuple to any point. Although I can see 

aplications in graphics (cycloids...), I do not think that this makes 

life easier for calculations. There are enough problems with unique 

maps, no need to make artificial ones.


Helen Read wrote:

> 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


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