Doubt regarding ode45 plotting

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.

Answer 1

[Torsten]

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.

[Pavan Kumar]

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]

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]

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]

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]

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]

Is it possible to use any other function in matlab in this situation?

[Torsten]

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]

Thanks a lot..Will try it and come back to you

[Pavan Kumar]

Hii Torsten,

your advise really helped. Thanks a trillion bro...

Pavan

Answer 2

[Sara]

ode45(@(t,x)DFG789(t,x,var_1),.....

Then the function becomes:

function dB = DFG789(Z1,B,var_1)

[Pavan Kumar]

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?