Plotting Level Curves after function

how do i plot level curves in matlab

such as c = 0, 0.5, 1, ..., 3.

i have already computed the code for the function

f (x, y) = (x2 + 3y2)e1−x2 −y2

over the domain −1 ≤ x ≤ 1, −1 ≤ y ≤ 1.

Answer 1

[Star Strider]

Use the contour function.

You can use fcontour, however it will not be possible to export its results to plot with contour.

[Torsten]

"fimplicit" might also be an option.

[Star Strider]

@Torsten — I considered that, however that could require at least one explicit loop, where contour could do all the ‘c’ values using the LevelList argument. I would have simulated it here, except that I have no idea whether ‘e’ is a variable or the exponential function exp.

Assuming ‘e’ because of that ambiguity, one approach could be —

syms x y 
f(x,y) = (x^2 + 3*y^2)*exp(1-x^2-y^2);
figure
fcontour(f, [-1 1 -1 1], 'LevelList',[0:0.5:3], 'Fill','on')
colormap(turbo)
colorbar
axis('equal')

.

[lateef]

i tried using the fcontour with my current code and im getting an error messsage

[lateef]

ive attached my currrent code i want to add level curves too using fcountour the code gets an error message

[Star Strider]

If you want to use a function handle, my code changes to:

f = @(x,y) (x.^2 + 3*y.^2).*exp(1-x.^2-y.^2);
figure
fcontour(f, [-1 1 -1 1], 'LevelList',[0:0.5:3], 'Fill','on')
colormap(turbo)
colorbar
axis('equal')

That is the only change necessary. The 'Fill','on' is optional.

Your code would work with contour or contourf, although not with fcontour, since fcontour creates its own matrices and does not take them as arguments.

.