How to improve a for

Hello, i want to do this operation:

f = -[Q(:,1)'*Q(:,1); Q(:,2)'*Q(:,2); Q(:,3)'*Q(:,3); Q(:,4)'*Q(:,4); Q(:,5)'*Q(:,5); Q(:,6)'*Q(:,6); Q(:,7)'*Q(:,7); Q(:,8)'*Q(:,8); Q(:,9)'*Q(:,9); Q(:,10)'*Q(:,10)];

i have thought to do this with a for

n=10;
i=1;
while i<n+1
    f(i,1)=-[Q(:,i)'*Q(:,i)]; %save in columns
    i=i+1;
end

but i think there must be some way to vectorize this easily. Could you help me?

Thank you.

Answer 1

[Azzi Abdelmalek]

-sum(Q.*Q)

Answer 2

[Jan]

The vectorization is better, but here is a cleaner and more efficient loop method:

f = zeros(10, 1);  % pre-allocate!!!
for k = 1:10
  f(k, 1) = -(Q(:,k)' * Q(:,k));
end

[Carlos]

Thank you so much. I think that the for loop is much better than mine before. Otherwise, how is the way to make the vectorization? Is it the answer of Azzi?

[Jan]

Yes, Carlos.

Answer 3

[Andrei Bobrov]

f = -dot(Q,Q).'