Re: VectorPlot on a Circle

*To*: mathgroup at smc.vnet.net*Subject*: [mg114798] Re: VectorPlot on a Circle*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Fri, 17 Dec 2010 03:30:17 -0500 (EST)*Reply-to*: hanlonr at cox.net

Look at Boole or RegionFunction With[{d = .041}, VectorPlot[{y, -x} Boole[1 - d < Sqrt[x^2 + y^2] < 1 + d], {x, -1, 1}, {y, -1, 1}]] With[{d = .041}, VectorPlot[{y, -x}, {x, -1, 1}, {y, -1, 1}, RegionFunction -> Function[{x, y}, 1 - d < Sqrt[x^2 + y^2] < 1 + d]]] Bob Hanlon ---- Dave Snead <dsnead6 at charter.net> 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