Your question is not very clear. First you're defining, M,K,N and F,
M=32;
K=1;
N=M-K;
F=exprnd(1,1,M);
Now you want to remove K elements from F starting smallest. But what is F_d? is it the sorted F in descending order? If so,
[F_d, index] = sort(F,'descend');
If you want to remove K elements from F, but the smallest ones, then,
F = F_d(index(1:N));
Now if you also want to remove K elements,
F_d = F_d(1:N);
now what is a and a_d? The values of F and F_d are stored in F and F_d.
