Removing specific elements from vector

I have an exponentially distributed vector "F" with "M" values. I need to remove "K" amount of values from "F" starting from the smallest values and I also need the vectors "a" and "a_d" that gives the values of "F" and "F_d" in descending order, respectively.

Everything works fine with my code, but I want "F_d" to be vector with "N" values, instead it gives me "M" values and on the "K" positions that I want to remove it puts Zeros. I know I can just remove the Zeros, but how can I make it work properly?

M=32; 
K=1; 
N=M-K; 
F=exprnd(1,1,M); 
[a, index] = sort(F,'descend'); 
a_d=a(1:end-K);
F_d(index(1:N))=a_d;

Answer 1

[KL]

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.

[Miroslav Mitev]

It is not what I was looking for. Anyway, thank you for your effort, I fixed the problem by myself. I accept your answer.