How to fix "fsolve stopped because it exceeded the function evaluation limit" while using fsolve function?

Recently, i'm trying to solve a nonlinear equation set by using "fsolve" . I created my personal function as the following:

function F = poSTAR_14(x,Hm_RI,at_RI,J)

F1=Hm_RI*x;

F2=at_RI*x-[1;0];

F3=x(1:J,1).^2+x(J+1:2*J,1).^2-ones(J,1);

F=[F1(:);F2(:);F3(:)];

end

Above is the function that contains 3 nonlinear equations and I saved it as a .m file with my main file.

Below is the part that I call the fsolve to solve my problem, where , are known vetors, is known scalar, initial point

Hm_R=real(Hm).*100;

Hm_I=imag(Hm).*100;

Hm_RI=[Hm_R,-Hm_I;Hm_I,Hm_R];

at_R=real(as_ele_Tx.');

at_I=imag(as_ele_Tx.');

at_RI=[at_R,-at_I;at_I,at_R];

w_R=real(conj(W_Tx));

w_I=imag(conj(W_Tx));

fun = @poSTAR_14;

x0 = [w_R;w_I];

x = fsolve(@(x)fun(x,Hm_RI,at_RI,J),x0);

But something is wrong with my code and the command window showed that,

Solver stopped prematurely.

fsolve stopped because it exceeded the function evaluation limit,

options.MaxFunctionEvaluations = 6.400000e+03.

Does it mean I should pick a better starting point or just set a larger "MaxFunctionEvaluations"?

I also modified the parameters as below,

options = optimoptions(@fsolve, 'MaxFunctionEvaluations', 10000, 'MaxIterations', 10000);

x = fsolve(@(x)fun(x,Hm_RI,at_RI,J),x0);

but the command window showed the same output.

So why it showed this output and how to fix it?

[Matt J]

The code you've posted won't run.

H=rand(30,64);
a=rand(2,64);
x0=rand(64,1);

poSTAR_14(x0,H,a,32)

Unable to perform assignment because the indices on the left side are not compatible with the size of the right side.

Error in solution>poSTAR_14 (line 9)
F(1)=Hm_RI*x;

function F = poSTAR_14(x,Hm_RI,at_RI,J)
F(1)=Hm_RI*x;
F(2)=at_RI*x-[1;0];
F(3)=x(1:J,1).^2+x((J+1):2*J,1).^2-ones(J,1);
F=[F1(:);F2(:);F3(:)];
end

[奥 刘]

@Matt J Hi, thanks for answering my question. I tried to run your code, and it showed,

Not enough input arguments.

Error in poSTAR_14 (line 4)

F3=x(1:J,1).^2+x(J+1:2*J,1).^2-ones(J,1);

Error in tempzz (line 7)

poSTAR_14(x0,H,a)

Maybe you missed the input of J?

[Matt J]

Even if you add it, it still won't run.

[奥 刘]

@Matt J Sorry, the function should be,

F1=Hm_RI*x;

F2=at_RI*x-[1;0];

F3=x(1:J,1).^2+x(J+1:2*J,1).^2-ones(J,1);

F=[F1(:);F2(:);F3(:)];

my bad.

[Matt J]

Yes, but without the input data like Hm and as_ele_Tx, there is still no way to run the code.

[奥 刘]

@Matt J

I attached the data files of Hm_RI and at_RI here.

as for the starting point x0, it can be achieved as,

weight0=ones(J,1).*exp(1j*(2*pi*randn(J,1)-pi));

w_R=real(conj(weight0));

w_I=imag(conj(weight0));

or just set it as

x0=[ones(J,1);zeros(J,1)];