Plot contours at a level I wish

All,

I have the following code:

close all
clc

N=linspace(10,110,40);
P=linspace(10,70,40);
[N,P]=meshgrid(N,P);

a=0.4;
b=0.01;
c=0.005;
d=0.3;

d/c
a/b

H=c*N-d*log(N)-a*log(P)+b*P;
f=mesh(N,P,H);
set(f,'EdgeAlpha',0.6)

hold on

contour3(N,P,H,[-2,-1.99,-1.98,-1.97,-1.96]);

contour(N,P,H,[-2,-1.99,-1.98,-1.97,-1.96]);

box on

xlabel('N-axis')
ylabel('P-axis')

rotate3d

commandwindow

I'd like to set the second set of contours at the bottom of the plot, at z=-2.5. Can someone show me how to do that?

Thanks

D.

Answer 1

[Teja Muppirala]

Here's one idea.

First change this line:

contour(N,P,H,[-2,-1.99,-1.98,-1.97,-1.96]);

to this (in order to get the handle of the contour object):

[~,h] = contour(N,P,H,[-2,-1.99,-1.98,-1.97,-1.96]);

And add this at the end: (to process each contour in series)

kids = get(h,'children');
set(gca,'zlimmode','manual');
for n = 1:numel(kids)
    set(kids(n),'zdata', min(zlim)+zeros(size(get(kids(n),'ydata'))))
end

Answer 2

[David Arnold]

Excellent! May I ask one more question? When I change the paper size and position, then rotate the view, the axis labels (in this case "Prey" and "Predator") always wind up in a poor position. How can I write code to move them close to the center of the axes after such a rotation of the view?

close all
clc

N=linspace(10,110,40);
P=linspace(10,70,40);
[N,P]=meshgrid(N,P);

a=0.4;
b=0.01;
c=0.005;
d=0.3;

d/c
a/b

H=c*N-d*log(N)-a*log(P)+b*P;
f=mesh(N,P,H);
set(f,'EdgeAlpha',0.6)

hold on

contour3(N,P,H,[-2,-1.99,-1.98,-1.97,-1.96]);

[c,h]=contour(N,P,H,[-2,-1.99,-1.98,-1.97,-1.96]);

kids = get(h,'children');
set(gca,'zlimmode','manual');
for n = 1:numel(kids)
    set(kids(n),'zdata', min(zlim)+zeros(size(get(kids(n),'ydata'))))
end

axis tight
box on

xlabel('Prey')
ylabel('Predator')
title('Closed periodic solutions.')

view(42,32)

set(gcf,'PaperSize',[4,3])
set(gcf,'PaperPosition',[0,0,4,3])
saveas(gcf,'closed','pdf')