Re: VectorPlot on a Circle

*To*: mathgroup at smc.vnet.net*Subject*: [mg114801] Re: VectorPlot on a Circle*From*: Helen Read <readhpr at gmail.com>*Date*: Fri, 17 Dec 2010 03:30:49 -0500 (EST)*References*: <ie297c$mrj$1@smc.vnet.net> <201012130852.DAA09458@smc.vnet.net> <iecqvv$bld$1@smc.vnet.net>

On 12/16/2010 5:51 AM, Dave Snead wrote: > Hi, > > I'm trying to do a vector plot but confine the vectors to a unit circle. > > VectorPlot[ > If[Abs[x^2 + y^2 - 1] == 0, {x, y}, {0, 0}], {x, -1, 1}, {y, -1, 1}] > only plots a couple of vectors, not the dense set of vectors that I want. > > and > VectorPlot[ > If[Abs[x^2 + y^2 - 1]<.1, {x, y}, {0, 0}], {x, -1, 1}, {y, -1, 1}] > plots lots of vectors but they're on an annulus rather than a circle. You could specify exactly what points to use. points = Table[{Cos[t], Sin[t]}, {t, 0, 2 \[Pi], \[Pi]/24}]; VectorPlot[{x, y}, {x, -1, 1}, {y, -1, 1}, VectorPoints -> points] -- Helen Read University of Vermont

**References**:**Re: vector/matrix indexed from zero***From:*Norbert Marxer <marxer@mec.li>