Weird discrepancy while plotting solutions of ode systems

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Viviana Arrigoni 2015-9-19

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评论： Viviana Arrigoni 2015-9-20

I am plotting the solutions of some ode systems which describe a biological model, but the graphs I got are a bit different from the ones presented in the papers. I am wondering if I am doing something wrong (maybe in interpreting the constants) or if it is possible that the same system may generate such different solution plots considering that I am using Matlab while the authors have plotted the graphs with Mathematica:

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Answer 1

bio lim 2015-9-20

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Without looking at the code, I don't think it is possible for us to answer your question.

Judging from the graphs, I can only tell that you shifted the graph to the right side about 25 hours, and your graph, especially the Biomass (Y(:,1)) looks much smoother.

As for the softwares, I don't think there would be any difference.

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Viviana Arrigoni 2015-9-20

在 MATLAB Online 中打开

Fine, well here's the model:

and here is my code. I first wrote this function in which the equations are described:

   function dydt = firstsystem ( t, y )
dydt = zeros(4,1);
dydt(1)=((0.16 * y(2))/(0.01+y(2)) - 0.0001*y(3))*y(1);
dydt(2)=(-0.16 * y(2)/((0.01+y(2))*31))*y(1);
dydt(3)=(0.3*y(4)/(10+y(4)))*y(1);
dydt(4)=((-0.3*y(4))/((10+y(4))*0.47))*y(1);

and then this script:

    tspan = [0 300];
yzero = [0.1 150 0 240];
[T,Y] = ode45 (@firstsystem, tspan, yzero);
plot (T,3*Y(:,1)/100,'m',T,Y(:,2),'g',T,Y(:,3),'b',T,Y(:,4),'c');

While plotting the first variable, I had to multiply it by 3/100, in order to obtain something more similar to the correst results.

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