can anyone help me to correct the matlab code?

function vdpd_qo_syn

clear all
clear all
figure(1)
%Computational Length and step size
n=100;   %total data legnth (n/h)
h=0.01;
%%%%%%%%%%%%%%%%%%%system 1%%%%%%%%%%%%%%%%   

alpha= 0.01;
beta = 9.74;
omegaf= 0.3;
gamma= 0.2;
W1= 0.3;
ff1 =0.4999;

%% Initial condition
x10 = 0.11; x20 = 0.2; 
%%%%%%%%%%%%%%%system 2%%%%%%%%%%%%%%%%   
e = 0.22;
a= 0.956;
b = 0.149;
ff2 =.59;
W2= 0.3;

%% Initial condition
x30 = 0.11; x40 = 0.2; 
%%%%%%%%%%%%%%%%%%coupling %%%%%%%%%%%%%%%%   
cou=0.2;
%time step and initial condition
tspan = 0:h:n;  
y0 = [x10; x20; x30; x40];
%[t,y] = ode45(@(t,x) f(t,x,a,b,beta,rho,ff1,W1,W2,ff2,cou),tspan,y0);   
%[t,y] = ode45(@(t,x) f(t,x,alpha,omegaf,beta,gamma,ff1,ff2,W1,W2,epsilon,alpha1,beta1,cou),tspan,y0);   
[t,y] = ode45(@(t,x) f(t,x,alpha,beta,omegaf,gamma,ff1,W1,e,a,b,ff2,W2,cou),tspan,y0);   


%% transient%%%%%%%%%%%%%%%%remove%%%%%%%%%%%%%%%
k=n/h;
k1=(k/2:k);
size(k1);
x1=y(k1,1); x2=y(k1,2);  x3=y(k1,3); x4=y(k1,4); ti=t(k1);

%plot the variable
%plot(x1,x2)
subplot(2,2,4);plot(t,y(:,1)); xlabel('t'); ylabel('x'); title('time series of qo oscillaor');
subplot(2,2,1); plot(x1,x2); xlabel('x'); ylabel('y'); title('Quintic oscillator '); 
subplot(2,2,2); plot(x3,x4); xlabel('x^P'); ylabel('y^P'); title('VdpD oscillator'); 
subplot(2,2,3); plot(x1,x3); xlabel('x'); ylabel('y'); title('Synchronization'); 
figure(2)
subplot(2,1,1);plot(ti,x1,'r',ti,x3,'b'); xlabel('Time(sec)'); ylabel('x1,y1'); 
subplot(2,1,2);plot(ti,x1,'r',ti,x3,'b'); xlabel('Time(sec)'); ylabel('x1,y1');
%figure(2)
% plot(ti,x2,'r',ti,x4,'b'); xlabel('Time(sec)'); ylabel('x2,y2');  
fprintf('Total length %d and the code taken transient after %d', k,k/2)



function dy = f(t,y,alpha,beta,omegaf,gamma,ff1,W1,e,a,b,ff2,W2,cou)        
x1 = y(1);    x2 = y(2);   x3 = y(3);    x4 = y(4);

%e1 = x3-x1;   
%e2= x4-x2;

%sys-I
dx1=x2+cou*(x3-x1);
dx2=-alpha*x2-omegaf*x1-beta*x1.^3- gamma*x1.^5+ff1*cos(W1*t);
%Sys II
u1 = -x4+x2-x3+x1;
u2 = -(omegaf-alpha +beta*x1.^2 +gamma*x1.^4)*x1 -b*x2.^3-(e+alpha)*x3 +e*x2.^2*x4 -f2*sin(W2*t)-f1*cos(W1*t);
dx3=x4+u1;
dx4=e*(1-x3.^2)*x4-a*x3+b*x3.^2+ff2*cos(W2*t)+u2;

dy = [dx1; dx2; dx3; dx4];

[KALYAN ACHARJYA]

Please be specific, so members can help you.

Answer 1

[DGM]

Just a guess, but f1 and f2 are undefined.

If i change them to ff1 and ff2, the code runs:

u2 = -(omegaf-alpha +beta*x1.^2 +gamma*x1.^4)*x1 -b*x2.^3-(e+alpha)*x3 +e*x2.^2*x4 -ff2*sin(W2*t)-ff1*cos(W1*t);

You'll have to decide if that substitution makes sense. I only made that change based on the context. I have no insight into what this code is doing.

[DGM]

What's wrong with the coupling parameter that you had defined originally?