Re: PolarPlot
- To: mathgroup at smc.vnet.net
- Subject: [mg87775] Re: PolarPlot
- From: dh <dh at metrohm.ch>
- Date: Wed, 16 Apr 2008 22:31:45 -0400 (EDT)
- References: <ftmu5p$50d$1@smc.vnet.net> <ftv938$80f$1@smc.vnet.net> <fu1u66$oom$1@smc.vnet.net>
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. Daniel 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 >