Issues with my Bifurcation Diagram

My code is completing but will not graph any data and i'm not sure why, I need to plot k againct c as my parameters

Can anyone else see the problem

thankyou

figure;

ax(1);

hold on

xlabel ('k');

ylabel ('C');

xlim([-2 2]);

ylim([0 40]);

dt = 0.01;

N = 10000;

for k=-2:0.1:10

c = zeros(N,1);

c(1)= 23;

t(1) = 0;

for i=1:N

t(i+1) = t(i) + dt;

c(i+1) = c(i) + dt*((1/10)*((c(i)-23)*(25-c(i))*(c(i)-29))-k);

end

plot(ax(1),k,c,'color','blue','marker','.');

end

[Torsten]

Maybe somebody can help if you report the complete error message.

You will have to plot c against t, not c against k.

[Emily Tabb]

i need to plot c against k, as it is in the equation and is the parameter that i am changing, will it be better if i just remove t?

Error was probably the wrong word, the code completes but when the figure presents itself there is nothing on it, there is no graph on it at all

Answer 1

[Star Strider]

One problem is that ‘ax(1)’ does not have anything assigned to it, at least in the posted code. Fixing that makes the axes magickally appear!

Beyond that, the code takes a while to run, so I changed ‘N’ to a value that does not time-out the online Run feature 55 second limit. It does not look like a bifurcation diagram, but at least now it plots.

figure;
    ax(1) = axes;
    hold on
    xlabel ('k');
    ylabel ('C'); 
    xlim([-2 2]);
    ylim([0 40]);

dt = 0.01;
N = 250;
for k=-2:0.1:10
        c = zeros(N+1,1);
        c(1)= 23;
        t(1) = 0;
        for i=1:N
            t(i+1) = t(i) + dt;
            c(i+1) = c(i) + dt*((1/10)*((c(i)-23)*(25-c(i))*(c(i)-29))-k);
        end
        plot(ax(1),k,c,'color','blue','marker','.');
end

.

[Emily Tabb]

Thankyou so much for you're help I'm not sure why it is not looking more like a bifurcation diagram is there a major issue you can see in the coding? I'm just trying to plot a bifurcation diagram from this equation dc/dt = 1/10(C-23)(25-C)(C-29) - k

Thanks

[Star Strider]

My pleasure!

I have no idea, although I suspect there is more to the equation tthan was posted.

My Answer specifically addresses the plotting problem.