RE: How to plot implicit function?

[Geordie McBain]

On Tue, 2006-10-10 at 18:05 +0200, TEJEDA HERNANDEZ, CESAR wrote:
> I would give values in a matrix and plot the matrix using 'contour'.

Yes, that's the best way to do it.

However, if you wanted to do the same thing for a function that was
expensive to evaluate, you might want to consider a path-following
technique.  

For example, for your example, using my function askirt.m from
http://www.aeromech.usyd.edu.au/~mcbain/stability/askirt.m , you could
do

octave:27> margin = askirt ([4; 0], [6; 0], inline ("norm (x) < 5"),
1e-1*[1;1], 1e-1, 1.1, -[Inf;Inf], [Inf;Inf], 4e3); 
octave:28> plot (margin(1,:), margin(2,:), "*-")

-- 
Geordie McBain
www.aeromech.usyd.edu.au/~mcbain