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ParametricPlot3D problem
*To*: mathgroup at smc.vnet.net
*Subject*: [mg110784] ParametricPlot3D problem
*From*: "Juan Fernando Herrera J." <juanfhj at gmail.com>
*Date*: Tue, 6 Jul 2010 05:02:32 -0400 (EDT)
I'm trying to plot electric field lines as tubes with a parametric
plot. I build a list with n points as
ptsA = BuildPointList[th]
where th is the angle of the field line. ptsA[[1]] is then the list of
points, and ptsA[[2]], ptsA[[3]] are lists giving two vectors
perpendicular to the field line at each point.
I go on to define
F[pts_,i_,t_]:=pts[[1, i]] + pts[[2, i]] Cos[t] + pts[[3, i]] Sin[t]
When I plot with
ParametricPlot3D[
F[ptsA, i, t],
{i, 1, n , 1},
{t, 0, 2 Pi}]
I obtain a field line as a tube. But when I try plotting two lines ptsA, ptsB as
ParametricPlot3D[
{F[ptsA, i, t],
F[ptsB, i, t]},
{i, 1, n, 1},
{t, 0, 2 Pi}]
I get ParametricPlot3D::ppfun: Argument {F[ptsA, i, t], F[ptsB, i, t]}
is not a list with three or four elements.
What's wrong here? Thanks
Juan Herrera
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