[Maxima] show gradient vectors orthogonal to level curves

[Adam Majewski]

Jaime Villate pisze:
> On Qua, 2009-10-21 at 18:31 +0100, Jaime Villate wrote:
>> I am trying to demonstrate that gradient vectors are orthogonal to
>>> contour lines.
> 
>> Please try the following:...
> 
> You can also get the plot you want with the following command:
> 
>   ploteq(y^2-x^2,[x,y],[x,-3,3],[y,-3,3],[vectors,"blue"]);
> 
> and then click on a few points.
> 
> Jaime


I have tied it :

/*
wxMaxima 0.7.6 http://wxmaxima.sourceforge.net
Maxima 5.16.3 http://maxima.sourceforge.net
Using Lisp GNU Common Lisp (GCL) GCL 2.6.8 (aka GCL)
Distributed under the GNU Public License. See the file COPYING.
Dedicated to the memory of William Schelter.
The function bug_report() provides bug reporting information.
(%i1) load("plotdf")$
plotdf(exp(-x)+y,[trajectory_at,2,-0.1])$

it works


(%i3) ploteq(y^2-x^2,[x,y],[x,-3,3],[y,-3,3],[vectors,"blue"]);
(%o3) ploteq(y^2-x^2,[x,y],[x,-3,3],[y,-3,3],[vectors,blue])

it does not work for  me

Also under

wxMaxima 0.8.3 http://wxmaxima.sourceforge.net
Maxima 5.19.2 http://maxima.sourceforge.net
Using Lisp GNU Common Lisp (GCL) GCL 2.6.8 (aka GCL)
Distributed under the GNU Public License. See the file COPYING.
Dedicated to the memory of William Schelter.
The function bug_report() provides bug reporting information.

plotdf does not work for me.

Regards

Adam