Lotka Volterra with an additional parameter
2 Ansichten (letzte 30 Tage)
Ältere Kommentare anzeigen
Khushi Patel
am 25 Sep. 2020
Kommentiert: Star Strider
am 25 Sep. 2020
I have attempted to model the equations provided below. the code keeps giving me an error when I try to plot the figure using the parameter k instead of t. I am trying to model the effect of varying k on the population dynamics for both prey and predator.
note: if I use plot(k, P) it gives me a complicated and entirely different graph that is unreadable.
Script Window:
tspan = [0, 400];
P0 = [200, 50];
k = [-1, 1];
[t,P] = ode45(@(t,P)lotkavolterra(t,P),tspan,P0);
plot(k,P(:,1),k,P(:,2)) %This section gives me the error. It works, however, if I use t instead of k.
function [dPdt] = lotkawithk(t,P)
alpha = 1;
beta = 0.05;
gamma = 0.05;
delta = 0.0025;
x = P(1);
y = P(2);
dPdt = zeroes(2,1);
dPdt(1) = alpha*x - (beta*x*y)/((log(exp(1)+t))^k);
dPdt(2) = (delta*x*y)/((log(exp(1)+t))^k) - (gamma*y);
end
0 Kommentare
Akzeptierte Antwort
Star Strider
am 25 Sep. 2020
I cannot imagine how you got that code to work at all, considering that the function you call in ode45 is not the function you posted!
Try this:
tspan = linspace(0, 400, 100);;
P0 = [200, 50];
k = [-1, 1];
for k1 = 1:numel(k)
[t,P] = ode45(@(t,P)lotkawithk(t,P,k(k1)),tspan,P0);
Pm{k1} = P;
end
figure
hold on
for k1 = 1:numel(k)
plot(t,Pm{k1}(:,1), t,Pm{k1}(:,2), 'DisplayName',sprintf('k = %d',k(k1))) %This section gives me the error. It works, however, if I use t instead of k.
end
grid
legend
function [dPdt] = lotkawithk(t,P,k)
alpha = 1;
beta = 0.05;
gamma = 0.05;
delta = 0.0025;
x = P(1);
y = P(2);
dPdt = zeros(2,1);
dPdt(1) = alpha*x - (beta*x*y)/((log(exp(1)+t))^k);
dPdt(2) = (delta*x*y)/((log(exp(1)+t))^k) - (gamma*y);
end
Note that ‘k’ is passed as a parameter.
Make appropriate changes to get different results.
6 Kommentare
Weitere Antworten (1)
Siehe auch
Kategorien
Mehr zu Line Plots finden Sie in Help Center und File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!