How to build a system of iteration for multiple interrelated variables?

Primarily, I have 5 variables - q1,q2,q3,q4 and ts. q1,q2,q3,q4 are dependent on ts and ts is also dependent on q1,q2,q3,q4. I have the initial values of all of these q1,q2,q3,q4 and ts. Then comes t2 which I get from the above 5 variables. and Then ts(new) = ts+t2. For this new ts, the values of q1,q2,q3 and q4 again change and we get new t2, and ts is changed again....the process should go on.

How do I develop this system in Matlab? I am new in matlab, but not very novice.

[jgg]

Why not just use a for loop?

 maxiter = 1000;

 q1 = [q10,q20,q30,q40]; %your initial values
 t1 = t0; %your initial values

 V = zeros(maxiter,5);
 V(1,:) = [q1,t1];

 for i = 2:maxiter
   t2 = my_t2_fun(V(i-1,:)); %your function to calculate t2
   t_next = t2 + V(i-1,5); %update t
   q_next = my_q_fun(t_next); %calculate the new vector of qs
   V(i,:) = [q_next,t_next];
 end

Something like this should work; just iterate forward using the old saved values. You'll get output in V.

[Mahbubur Rahman]

Thanks a lot for the reply. I am trying with this one, but in the line 5; it is showing. What did you mean by 6. Thanks in advance.

 Subscripted assignment dimension mismatch.

 Error in Untitled2 (line 5)
 V(1,:) = [q1,t1];

[jgg]

Sorry, this should be V = zeros(maxiter,5); instead of 6; I miscounted your variables.

[Mahbubur Rahman]

Thanks a lot, jgg. I followed your coding first and eventually was able to solve it using my own ideas.

But I am looking for a new suggestion now. If you look at this code - the number of iteration n is the iteration counter but for me it is also the seconds of the system (with max time 8 sec). I need the n (or sec which can be fractional) for which ts = 1000 inside the loop.

 a = 5;
b =  22;
c = 13;
d = 4;
ts = 50+ 4*b;
stamp = zeros(1,8);
for n = 1:8
   ta = 1+(b+a)/n*c;
   ts = ta +ts; 
   b = b+1;
   a = a + b/2;
   c = c-.5;
   stamp(n) = ts; 
end 
disp(d)
disp(a)