Subscript indices must either be real positive integers or logicals.

k_est=k_p(bb,:); 
    XF_est=xf(bb).XF;            
num_2=num_2+1; 
kkk2(num_2,:)=k_est;

for iii=1:length(k_est)
    X_re(k_est(iii))=XF_est(iii);
end

what is the problem in my four loop

Answer 1

[Star Strider]

What is k_est and what is its size (what are its dimensions)?

[irfan]

1*2 complex double and xf_est dimensions is 2*1 complex double

[Walter Roberson]

If k_est is a complex double, then how can you use it to index X_re in your statement

X_re(k_est(iii))=XF_est(iii);

??

Are you trying to define a "formula", sort of like a definition that for function f,

f(sqrt(2)) = 4.1293;
f(3.5) = 7.893;

?? If you are, then that is not possible in MATLAB, except in the case of a symbolic function being defined.