Fmincon stopped because the size of the current step is less than the default value of the step size tolerance...How can I solve this?

Question

Ksss 2021-6-25

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/865235-fmincon-stopped-because-the-size-of-the-current-step-is-less-than-the-default-value-of-the-step-size

评论： Ksss 2021-6-25

This is my coding

U=[0.04854 0 0 0; 0.03483 0.03125 0 0; 0.02477 0.02223 0.04000 0; 0.01738 0.01550 0.02807 0.05263];
m=[1.6378; 1.1753; 0.8359; 0.5867];
n=4;
fun=inline('200*0.5.^0.8+1000*0.5.^0.8*x(1).^2+200*0.3.^0.8+1000*0.3.^0.8*x(2).^2+200*0.4.^0.8+1000*0.4.^0.8*x(3).^2+200*0.5.^0.8+1000*0.5.^0.8*x(4).^2');
x0=[1 1 1 1];
a=[5;5;5;5];
b=[200;200;200;200];
A=[-200 0 0 0; 0 -200 0 0; 0 0 -200 0; 0 0 0 -200];
B=inv(U)*(a-m);
LB=[0 0 0 0];
UB=[1 1 1 1];
[x,fval]=fmincon(fun,x0,A,B,[],[],LB,UB,[]);
x;
fval;
L=ones(4,1);
for i=1:n
    L(i)=200*(1-x(i));
end;
L;
L2=U*L+m;

But after running it, it shows

Local minimum possible. Constraints satisfied.
fmincon stopped because the size of the current step is less than
the default value of the step size tolerance and constraints are 
satisfied to within the default value of the constraint tolerance.
<stopping criteria details>