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Re: PolarPlot

• To: mathgroup at smc.vnet.net
• Subject: [mg87678] Re: PolarPlot
• From: Helen Read <hpr at together.net>
• Date: Tue, 15 Apr 2008 05:54:28 -0400 (EDT)
• References: <ftmu5p$50d$1@smc.vnet.net> <ftv938$80f$1@smc.vnet.net>
• Reply-to: HPR <read at math.uvm.edu>

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