Subject: show gradient vectors orthogonal to level curves
From: Jaime Villate
Date: Wed, 21 Oct 2009 18:31:21 +0100
On Qua, 2009-10-21 at 10:02 -0400, G. Jay Kerns wrote:
> I am trying to demonstrate that gradient vectors are orthogonal to
> contour lines. I have tried lots of things, but nothing seems to be
> exactly right. Here's some of what I tried.
>
> 1) I can get plotdf to plot the vector field nicely, but then I can't
> seem to add the contour lines to the plot... it is an ODE plot, after
> all, which is concerned with trajectories and the like.
Please try the following:
1- Use the plotdf command.
2- Click at some points where you want fieldlines to be plotted.
3- Click on the "Config" menu button.
5- Delete the word "red" in the field "fieldlines" and enter another
color in the field "curves". For instance, you may write black or green.
6- Click on the "ok" button.
7- Click on the points where you want contour lines to be plotted.
I hope this helps.
Best regards,
Jaime