can i use more than 1 function in same m. file ? because i want to use multiple function for adapting frequency

Hello

i want to simulate using multiple oscillators.

following figure is showing what i want to do ..

the following code is having only one oscillator. I want to simulate using 2 or more oscillators. anyone is having idea how to do simulate with multiple oscillator ?

///////////////////////////////////////////

adaptive hopf oscillator function (instead of 1 i want to use 2 same function)

///////////////////////////////////////////

function dz = myeqd(t,y,ti,xd)

dz = zeros(3,1);

mu=0.2;

r= sqrt(y(1)^2 + y(2)^2);

K=100;

F=interp1(ti,xd,t);

dz(1)= (mu - r^2)*y(1) - y(3)*y(2) +K*F;

dz(2) = (mu - r^2)*y(2) + y(3)*y(1);

dz(3) = (-K*F) * (y(2)/sqrt(y(1)^2 + y(2)^2));

///////////////////////////////////////////////////

main code

///////////////////////////////////////////////////

Tspan= 0:0.001:20; % time vector

f0=100;

f1=400;

fi = chirp(Tspan,f0,20,f1,'quadratic');

ti=Tspan;

[T,Y]=ode45(@(t,y) myeqd1(t,y,ti,fi),Tspan,[1;1;90]);

plot (T,Y(:,3));

[ChristianW]

Just curious, why not use 1 ODE y' = f(t,y) with all states in statevector y?

% Osci#1
mu = 0.2; K = 100;
r = sqrt(y(1)^2 + y(2)^2);
dz(1) = (mu - r^2)*y(1) - y(3)*y(2) +K*F;
dz(2) = (mu - r^2)*y(2) + y(3)*y(1);
dz(3) = (-K*F) * (y(2)/r);

% Osci#2
mu2 = 0.2; K2 = 100;
r2 = sqrt(y(4)^2 + y(5)^2);
dz(4) = (mu2 - r2^2)*y(4) - y(6)*y(5) +K2*F;
dz(5) = (mu2 - r2^2)*y(5) + y(6)*y(4);
dz(6) = (-K2*F) * (y(5)/r2);

[Aniket]

Actually i am searching a way how to do it ... if you are suggesting me this i will try this one..

thanks

Answer 1

[ChristianW]

1. The attempt having myeqd1, myeqd2, myeqd3, ... and then solve them with ode45(myeqd1,...); ode45(myeqd2,...); ... etc is bad in general.
2. At your figure the oscillators are connected. If they influence each other, you need all oscillators in one ODE.
3. Whats the difference between Osci#1 and #2? Only mu and K?
4. My example above only shows that possibility. If you try it, you should still use "multiple functions":

function dy = myeqd(t,y,ti,xd)
dy = zeros(size(y));
F = interp1(ti,xd,t);
dy(1:3) = Osci(y(1:3),F,0.2,100); % Osci#1,  Osci(y,F,mu,K)
dy(4:6) = Osci(y(4:6),F,0.1,120); % Osci#2

function dz = Osci(z,F,mu,K)
r = sqrt(z(1)^2 + z(2)^2);
dz = [ (mu - r^2)*z(1) - z(3)*z(2) + K*F
      (mu - r^2)*z(2) + z(3)*z(1)
     -K*F * z(2)/r ];

[Aniket]

Hello Christian

1) in figure the oscillators are not connected. the both oscillators having common input that is external input F(t).

2 )their output will be added and get the final result.

3) the differences between oscillators are mu and K .

4)yes i have tried your way and i think it is working.

5) actually i want to give negative feedback from output to input side. how should i give it ? do you have any idea ?

[ChristianW]

F = interp1(ti,xd,t)-(y(3)+y(6));

[Aniket]

hello Christian,

I have add feedback but results are becoming zeros i don't why ? you have any idea ? i am plotting output by using summation "sum_out = Y(:,3)+Y(:,6)"

if i am adding feedback , i am getting following curve ,its not adapting

code

***************

function

****************

function dz = myeqd(t,y,ti,xx)

dz = zeros(6,1);

mu = 0.3;

r= sqrt(y(1)^2 + y(2)^2);

K1=500;

K2 = 500;

F=interp1(ti,xx,t)-(y(3)+y(6));

%osc1

dz(1)= (mu - r^2)*y(1) - y(3)*y(2) +K1.*F;

dz(2) = (mu - r^2)*y(2) + y(3)*y(1);

dz(3) = (-K1.*F) * (y(2)/sqrt(y(1)^2 + y(2)^2));

%osc2

dz(4)= (mu - r^2)*y(4) - y(6)*y(5) +K2.*F;

dz(5) = (mu- r^2)*y(5) + y(6)*y(4);

dz(6) = (-K2.*F) * (y(5)/sqrt(y(4)^2 + y(5)^2));

**************************************

main code

***************************

time = 0:0.001:20;

xx = chirp(time,100,10,400,'linear');

ti=time;

[T,Y]=ode45(@(t,y) myeqd(t,y,ti,xx),time,[5;5;90;5;5;90]);

sum_out = Y(:,3)+Y(:,6);

plot (T,sum_out)

Answer 2

[Walter Roberson]

Yes, it is quite valid to have more than one function in a .m file.

Only the first of the functions (the one the file is named with) will be directly callable from outside the .m file; other .m files would need to somehow have been given a function handle before they could call the other functions.

In your situation where you are passing in an anonymous function, that is sufficient for ode45 to get the function handle to be able to call the function referred to in the anonymous function.

[Aniket]

I have tried more than one function in single m.file but it gives me error. Ok, I want to create a group of oscillator function like in the above figure mentioned , so that external input frequency i can adapt and i can call these group of funtion from my main m.file. how should i crate it in matlab ?

[Walter Roberson]

What error did you encounter when you tried to put multiple functions in the same file?