Re: ListVectorPlot - plotting at specific points

*To*: mathgroup at smc.vnet.net*Subject*: [mg112596] Re: ListVectorPlot - plotting at specific points*From*: "David Park" <djmpark at comcast.net>*Date*: Wed, 22 Sep 2010 01:57:07 -0400 (EDT)

Whenever you have a List plot, you could also consider drawing the individual objects in your own Table or by using Map. So here are a set of random vectors tangent to a sphere: randomSphereArrow[] := Module[ {\[Theta]0 = RandomReal[{0, \[Pi]}], \[Phi]0 = RandomReal[{0, 2 \[Pi]}], sphere, d\[Theta], d\[Phi], position, direction}, sphere[\[Theta]_, \[Phi]_] := {Cos[\[Phi]] Sin[\[Theta]], Sin[\[Phi]] Sin[\[Theta]], Cos[\[Theta]]}; d\[Theta][\[Theta]_, \[Phi]_] = D[sphere[\[Theta], \[Phi]], \[Theta]]; d\[Phi][\[Theta]_, \[Phi]_] = D[sphere[\[Theta], \[Phi]], \[Phi]]; position = sphere[\[Theta]0, \[Phi]0]; direction = 0.5 Normalize[ RandomReal[{-1, 1}] d\[Theta][\[Theta]0, \[Phi]0] + RandomReal[{-1, 1}] d\[Phi][\[Theta]0, \[Phi]0]]; {Point[position], Arrow[{position, position + direction}]} ] Graphics3D[ {{Opacity[.6], Orange, Sphere[]}, Table[randomSphereArrow[], {5}]}, Lighting -> "Neutral", SphericalRegion -> True, RotationAction -> "Clip", Boxed -> False ] David Park djmpark at comcast.net http://home.comcast.net/~djmpark/ From: gopher [mailto:gophergoon at gmail.com] Contrary to the documentation, listing pairs of points and vectors i.e ListVectorFieldPlot[{{{0, 0}, {1, 1}}}] gives an error: ListVectorPlot::vfldata: {{{0,0},{1,1}}} is not a valid vector field dataset or a valid list of datasets. .After a lot of searching I found that the deprecated << "VectorFieldPlots`" ListVectorFieldPlot[{{{0, 0}, {1, 1}}}] does work, but doesn't look as nice, especially the 3d version. Various settings of the VectorPoints options also don't work. Is there a solution? I am trying to make some simple examples of vector fields on spheres to illustrate the Hairy Ball theorem. Abhishek