Re: VectorPlot on a Circle

*To*: mathgroup at smc.vnet.net*Subject*: [mg114805] Re: VectorPlot on a Circle*From*: "Dave Snead" <dsnead6 at charter.net>*Date*: Fri, 17 Dec 2010 03:31:34 -0500 (EST)*References*: <ie297c$mrj$1@smc.vnet.net> <201012130852.DAA09458@smc.vnet.net> <201012161049.FAA11856@smc.vnet.net> <086FCBD6-0907-4B16-8A41-48E4A8258A16@trm.uni-leipzig.de>

Hi Patrick, Thanks, but VectorPlot[{x, y}, {x, -1, 1}, {y, -1, 1}, RegionFunction -> Function[{x, y}, x^2 + y^2 < 1]] plots vectors on the unit disk, I just want to define the vectors on the unit circle. What I would like is something like VectorPlot[{x, y}, {x, -1, 1}, {y, -1, 1}, RegionFunction -> Function[{x, y}, x^2 + y^2 == 1]] but this function only does a sparse plot of the vectors, and some of them are not on the circle! I'd like to know if Mathematica has the capability to restrict these vectors to a one dimensional, rather than a two dimensional region and do a decent plot. Cheers, Dave -----Original Message----- From: Patrick Scheibe Sent: Thursday, December 16, 2010 5:08 AM To: Dave Snead Cc: mathgroup at smc.vnet.net Subject: [mg114805] Re: VectorPlot on a Circle Hi, what about VectorPlot[{x, y}, {x, -1, 1}, {y, -1, 1}, RegionFunction -> Function[{x, y}, x^2 + y^2 < 1]] ? Cheers Patrick On Dec 16, 2010, at 11:49 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. > > Is there any way to do this? > > Or more generally is there any way to confine the vectors to a curve. > Or, kicking the dimension up by 1, can VectorPlot3D confine the vectors > to a surface? > > Thanks, > Dave Snead > >

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

**VectorPlot on a Circle***From:*"Dave Snead" <dsnead6@charter.net>