Group Abstract Group Abstract

Message Boards Message Boards

0
|
128 Views
|
3 Replies
|
0 Total Likes
View groups...
Share
Share this post:

Does this plot in cylindrical coordinates look correct?

Posted 2 days ago

I'm trying to create a 3D plot in cyclindrical coordiates using ParametricPlot3d. I'd just like to know if I'm getting it right. Can someone check to see if this looks right?

The function in cylindrical coordinates is z = (1-2r) * Sin[t] / r^2, where r is the radius, t is the polar angle theta, and z is the z coordinate.

(Edit): I know the rsin[t] and rcos[t] in the x and y arguments of the plot look reversed, but this plot actually represents a vertical cross section through the center of a sphere with charge density given by z. The r and t variables are the radius and polar angle in spherical coordinates of the spherical charge density, but here that vertical cross section has been rotated to be located in the horizontal x-y plane of the plot.

Parametric plot in cylindrical coordinates

POSTED BY: Chris Cantrell
3 Replies

Fixed some stuff. Due to the t variable being a polar angle in spherical coordinates, I've changed the range to only {t,0,Pi}.

Charge density

POSTED BY: Chris Cantrell

It is correct, but the choice of parameters makes it misleading as to the behaviour of the function. I would do it like this:

ParametricPlot3D[{r*Cos[t], r*Sin[t], (1 - 2 r)*Sin[t]/r^2},
 {r, 0, 3}, {t, 0, 2 Pi},
 PlotRange -> {3 {-1, 1}, 3 {-1, 1}, 3/2 {-1, 1}},
 BoxRatios -> 1]
POSTED BY: Gianluca Gorni

You're right, your way of doing it does show a lot more features. The problem I was solving included a constant R term as a value of r, and since I can't plot a function with an undefined constant, I just set R=1. Since the function in the problem doesn't extend past R, I just decided not to plot past r=R=1. I like what you did with the PlotRange, though, so I'll keep that in mind going forward.

POSTED BY: Chris Cantrell
Reply to this discussion
Community posts can be styled and formatted using the Markdown syntax.
Reply Preview
Attachments
Remove
or Discard