using fimplicit function to plot

I'm trying to make a plot using the fimplicit function but the figure is empty.

zf(1) = figure(1);
za(1) = axes;
c = -4:2:4;
fimplicit(@(x,y) y.^2 - x.^2- c);

Answer 1

[Ameer Hamza]

For a single graph, c must be a scalar. If you want to plot the graph for all values in c, you can use for-loop or arrayfun() (kind of implicit for-loop)

zf(1) = figure(1);
za(1) = axes;
hold(za(1))
C = -4:2:4;
arrayfun(@(c) fimplicit(@(x,y) y.^2 - x.^2 - c), C);

[Maria Galle]

How would I plot the graph for all values of c using a for loop? I tried writing the code but get the plot for one value of c.

for c=-4:2:4
zf(1) = figure(1);
za(1) = axes;
fimplicit(@(x,y) y.^2 - x.^2- c);
end

[Ameer Hamza]

Move figure() and axes() out of for loop

zf(1) = figure(1);
za(1) = axes;
hold(za(1));
for c=-4:2:4
fimplicit(@(x,y) y.^2 - x.^2- c);
end

Answer 2

[John D'Errico]

As an alternative to the use of fimplicit, you can simply think of this as a contour plot. That is essentially all fimplicit does.

c = -4:2:4;

fxy = @(x,y) x.^2 - y.^2;
H = fcontour(fxy,[-5,5, -5,5],'LevelList',c);

Either way works. A contour plot has the virtue that you can create all level lines in one call and no need to loop.