how can I use "for loop" in this to get a correct result?

clc
%defining constant
ti = 0; %inital time
tf = 100E-4;% final time
tspan=[ti tf];
o = 2E5;  % detuning frequency
tc = 30E-9;  %photon life time in cavity
tf = 230E-6;  %flouroscence lifetime
a1 = 0.1; %round trip loss
a2 = 0.1;
P1 = 0.2;  %pump strenght
P2 = 0.2;
kc = 3E-3; %critical coupling strength
s =  0.17;
k = s.*kc;
%I = 1; %saturation intensity
V = 1;

% define function
%y(1) = A1
%y(2) = A2
%y(3) = G1
%y(4) = G2
%y(5) = phase difference

f = @(t,y) [  
              (((y(3)./V) - a1) * y(1) + k * y(2) * cos(y(5))) ./ tc;
                 
            (((y(4)./V) - a2) * y(2) + k * y(1) * cos(y(5))) ./ tc;
                  
                    (P1 - ((y(3)./V) * (((abs(y(1)))^2 ./I) + 1))) / tf;
                     
                    (P2 - ((y(4)./V) * (((abs(y(2)))^2 ./I) + 1))) / tf;
                  
                   o - (k / tc) * (((y(1) ./ y(2)) + (y(2) ./ y(1))) * sin(y(5)));
                                    
                                      ];


I =1:1:100;
Vf = zeros(length(I),1) ; 
for i = 1:length(I)
     [T,Y] = ode45(f,tspan,[1;1;0;0;0].*10E-2);
     Vf(i) = (2.*(((mean(Y(:,1).*Y(:,2).*cos(Y(:,5)))).^2 + (mean(Y(:,1).*Y(:,2).*sin(Y(:,5)))).^2).^0.5))/(mean((Y(:,1)).^2)+mean((Y(:,2)).^2));
end

Unrecognized function or variable 'I'.

Error in solution (line 31)
(P1 - ((y(3)./V) * (((abs(y(1)))^2 ./I) + 1))) / tf;

Error in odearguments (line 92)
f0 = ode(t0,y0,args{:}); % ODE15I sets args{1} to yp0.

Error in ode45 (line 107)
odearguments(odeIsFuncHandle,odeTreatAsMFile, solver_name, ode, tspan, y0, options, varargin);

disp(Vf)

in this how I should apply for loop to get Vf for the different value of I ?

Answer 1

[Walter Roberson]

Move the assignment to f to before the

for i = 1:length(I)

Your call to ode45 within the loop depends upon f already having been defined.

You might as well delete the last lines

%initial consitions
[T,Y] = ode45(f,tspan,[1;1;0;0;0].*10E-2);

Note that your f value is independent of the value of i or I so every time through the for loop you are calculating exactly the same thing.

[SAHIL SAHOO]

I done what you said but there is no result.

[Torsten]

clc
%defining constant
ti = 0; %inital time
tf = 100E-4;% final time
tspan=[ti tf];
o = 2E5;  % detuning frequency
tc = 30E-9;  %photon life time in cavity
tf = 230E-6;  %flouroscence lifetime
a1 = 0.1; %round trip loss
a2 = 0.1;
P1 = 0.2;  %pump strenght
P2 = 0.2;
kc = 3E-3; %critical coupling strength
s =  0.17;
k = s.*kc;
%I = 1; %saturation intensity
V = 1;

% define function
%y(1) = A1
%y(2) = A2
%y(3) = G1
%y(4) = G2
%y(5) = phase difference

f = @(t,y,I) [  
              (((y(3)./V) - a1) * y(1) + k * y(2) * cos(y(5))) ./ tc;
                 
            (((y(4)./V) - a2) * y(2) + k * y(1) * cos(y(5))) ./ tc;
                  
                    (P1 - ((y(3)./V) * (((abs(y(1)))^2 ./I) + 1))) / tf;
                     
                    (P2 - ((y(4)./V) * (((abs(y(2)))^2 ./I) + 1))) / tf;
                  
                   o - (k / tc) * (((y(1) ./ y(2)) + (y(2) ./ y(1))) * sin(y(5)));
                                    
                                      ];


I =1:1:100;
Vf = zeros(length(I),1) ; 
for i = 1:length(I)
     [T,Y] = ode45(@(t,y)f(t,y,I(i)),tspan,[1;1;0;0;0].*10E-2);
     Vf(i) = (2.*(((mean(Y(:,1).*Y(:,2).*cos(Y(:,5)))).^2 + (mean(Y(:,1).*Y(:,2).*sin(Y(:,5)))).^2).^0.5))/(mean((Y(:,1)).^2)+mean((Y(:,2)).^2));
end
plot(I,Vf)

[SAHIL SAHOO]

ohh okay I got it, thanks