Trying to plot 3-d

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Avan Al-Saffar
Avan Al-Saffar 2014-8-8
评论： Yu Jiang 2014-9-3
My equation is
dxdt=N0*sin(omega*t)*x*(1-x/K);
N0=1:1:10;
omega=1:1:10;
I want to plot 3-D for N0,omega,Xmax and Xmean.
I am trying with the following code but it does not work.
function RunOsciliationsky3D
N0all= 1:1:10;
N=length(N0all);
omegaall= 1:1:10;
M=length(omegaall);
Pmax=zeros(N,M);
Pmean=zeros(N,M);
Pall=[Pmax,Pmean];
x=size(Pall);
for i=1:N
for j =1:N
[t,x]=ode45(@osciliation,[0 100],0.1,[],N0all(i),10,omegaall(j));
Pall(i,j)=x;
end
end
[N0x,omegay]=meshgrid(N0all,omegaall);
h=mesh(N0x,omegay,Pall);
1;
  1 个评论
Andy L
Andy L 2014-8-8
What error are you getting? I have tried copying and pasting but the function in your optimisation function isn't included.

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Yu Jiang
Yu Jiang 2014-8-8
See the files I revised as attached. It can generate Pmean. Similarly you can plot Pmax. Notice that it is not clear what K is, so I let it be 0.15. I also force N0 to take negative values since positive values make the system unstable.
Hope it helps.
- Yu
  2 个评论
Avan Al-Saffar
Avan Al-Saffar 2014-9-1
Dear Yu Jiang
Thank you for your previous help, but I need more help please if you have any advice?
I've chosen K=10 and N0 to get a positive values. I got the result which I am not happy with it and I got this error message:
Warning: Failure at t=8.083150e+01. Unable to meet integration tolerances without reducing the step size below the smallest value allowed (2.273737e-13)at time t.
> In ode45 at 308
In Runanswertest at 13
Warning: Failure at t=8.701882e+01. Unable to meet integration tolerances without reducing the step size below the smallest value allowed (2.273737e-13) at time t.
> In ode45 at 308
In Runanswertest at 13
Warning: Failure at t=3.011651e+01. Unable to meet integration tolerances without reducing the step size below the smallest value allowed (5.684342e-14) at time t.
> In ode45 at 308
In Runanswertest at 13
Warning: Failure at t=5.698339e+00. Unable to meet integration tolerances without reducing the step size below the smallest value allowed (1.421085e-14)at time t.
> In ode45 at 308
In Runanswertest at 13
Note: I thought to remove the initial transient period or just to reduce the time step but I am really confused about this code .
Yu Jiang
Yu Jiang 2014-9-3
When N0 is positive, the system can easily become unstable. Therefore, the initial condition should be reduced.
Please make the three changes based on the code I provided.
Line 12 of RunOsciliationsky3D.m : Change 0.1 to 0.01 or less
Line 2 of oscillation.m: Change K = 1 to K = 10
Line 3 of oscillation.m: Change x/0.15 to x/K.
This should work.

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