While loop doesn't start

Question

Nader Mohamed 2021-10-29

0
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https://ww2.mathworks.cn/matlabcentral/answers/1574623-while-loop-doesn-t-start

回答： Walter Roberson 2021-10-29

I'm trying to run a while loop until my error reaches the tolerance. But this loop doesn't start. I tried running it without the while loop (putting it manually the parameters) and it workd, but when I want to loop it it doesnt even start, no errors.. My goal here is to find the paramateres b and k that match the minimum error between the sampled solution (y2data) and the numerical solution

 toll = 10e-12;
 b = 0;
 k = 0;
 err = 0;
 res = [];
while(err>toll)
     
    findbk = @(t,y) [y(3);y(4);k/J1 * y(2) - k/J1 * y(1);T0/J2 - b*y(4)/J2 - (k/J2)*(y(2)-y(1))];
     
     [t,y] = ode45(@(t,y) findbk(t,y),[0:0.01:10],[0,0,0,0]);
     
     fun = @(b,k) T0/J2 - (b/J2).*y(:,4) - ((k/J2).*(y(:,2)-y(:,1)));
     
     err = abs(norm(y2data - fun(b,k)));
     
     res = [res;err];
     
     b = b + 0.01;
     
     k = k + 0.1;
end