Modeling Lotka-Volterra using ode23

Question

Jovos 2016-4-8

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https://ww2.mathworks.cn/matlabcentral/answers/277852-modeling-lotka-volterra-using-ode23

回答： Torsten 2016-4-8

采纳的回答： Torsten

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I have a question like this. I wonder if my code is correct.

The Lotka-Volterra predator-prey model :

dx/dt =px−qxy

dy/dt =rxy−sy

where x(t) and y(t) are the prey and predator population sizes at time t, and p,q, r, and s are biologically determined parameters. Consider p = 0.4, q = 0.4, r = 0.02, s =2.0, x(0) = 100, y(0) = 8.

 function prey
 %Predator-prey Model
 clc;clear;
 y0 = [100;8];
 soln = ode23(@f2,[0 100],y0)
 t = linspace(0,30,60);
 y(:,1)=deval(soln,t,1); %Prey
 y(:,2)=deval(soln,t,2); %Predator
 figure
 plot(t,y(:,1),'-o',t,y(:,2),'--');
 hold on;grid on;
 legend('Prey','Predator');
 xlabel('Time');
 ylabel('Population');
 hold off;
 end
 %Predator-prey function
 function dxdt = f2(t,x)
 dxdt = [0;0];
 p =0.4; q = 0.4; r = 0.02; s = 2.0;
 dxdt(1) = p*x(1)-q*x(1)*x(2);
 dxdt(2) = r*x(1)*x(2)-s*x(2);
 end