Doubt regarding ode45 plotting

2015 1 27
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更新时间：2015 2 3
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Dear Friends,
I need to plot ABS(B(1)) Vs delk in the following program code. How can i include delk variable in the ode45 function calling line.

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Torsten
Torsten 2015-1-28

0 个投票

Please make more clear what you try to plot.
As far as I can see, delk is a model parameter (scalar).
B is a vector (solution at different times).
You can't plot a vector over a scalar.
I guess you want to plot different solutions B over time for different values of delk.
For this puropse, you have to generate different solutions B (e.g. in a loop in which you call ODE45 several times for changing values of delk).
Best wishes
Torsten.

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Pavan Kumar
Pavan Kumar 2015-1-28
编辑：Pavan Kumar 2015-1-28
Hi Torsten.
Thanks for your answer.
In my program, delk is a function of kp,ks and ki which are in turn dependent on Lp,Ls and Li respectively. So,delk is unique for each value of Ls,Lp and Li and will be continous for a range of Ls as shown.This inturn makes Abs(B(1)) continous function of Ls.I need to plot Abs[B(1)]^2 vs delk in my program
Torsten
Torsten 2015-1-28
Again my question:
For each value of L_s, you get a function B(1) over the interval [0 3] in your example above.
How do you want to plot a function (B(1)) over a scalar (L_s) ?
Best wishes
Torsten.
Pavan Kumar
Pavan Kumar 2015-1-28
Torsten,
As mentioned above,Change in Ls changes delk which inturn changes B(1).
It would be a 3-D plot with abs[B(1)],Z1 and delk on each of the axis.
Pavan Kumar
Pavan Kumar 2015-1-29
Hii Torsten,
I don't know if i am right or wrong.But, i followed the avove code for constant delk and got right results so i am following the same for variable delk.
Do advise me.
Pavan
Torsten
Torsten 2015-1-29
The code you show in the above picture will not run with MATLAB.
Since delk in function DFG789 is a vector, dB will also be a vector.
But dB(1) is a scalar which gives a dimension mismatch.
Best wishes
Torsten.
Pavan Kumar
Pavan Kumar 2015-1-29
Is it possible to use any other function in matlab in this situation?
Torsten
Torsten 2015-1-29
I already gave you the solution for this problem:
Call ODE45 in a loop in which you calculate the solution for B(1) for several values of delz.
Delk=[1:20];
for i=1:20
delk=Delk(i)
[Z1,B] = ode45(@(t,x)DFG789(t,x,delk),[0 3],[(0.1) 0 1]);
Z1_complete(i,:,:)=Z1(:,:);
end
Best wishes
Torsten.
Pavan Kumar
Pavan Kumar 2015-1-29
Thanks a lot..Will try it and come back to you
Pavan Kumar
Pavan Kumar 2015-2-2
Hii Torsten,
your advise really helped. Thanks a trillion bro...
Pavan

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Sara
Sara 2015-1-27

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ode45(@(t,x)DFG789(t,x,var_1),.....
Then the function becomes:
function dB = DFG789(Z1,B,var_1)

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Pavan Kumar
Pavan Kumar 2015-1-28
编辑：Pavan Kumar 2015-1-28
Hii Sara, Thanks for the advise.
I made the following changes
[Z1,B] = ode45(@(t,x)DFG789(t,x,delk),[0 3],[(0.1) 0 1],delk); and
function dB = DFG789(Z1,B,delk)
However, when i try to execute
plot(delk,abs(B(:,1)).^2);
i get the following errors. What can i do?

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