reverse indexing with conditions

Let A = [1 2 4 6 10], I want to find the indices of the matrix for which the element less than 5.

So if I say: A < 5, then it will return [1 1 1 0 0]. How can I proceed to get the index of all those 1's?

Thanks

Answer 1

[TastyPastry]

idx = 1:numel(A);
mask = A < 5;
idx = idx(mask);

[cgo]

thanks

Answer 2

[Thorsten]

To get numerical indices, use find

 idx = find(A < 5);

You can also use logical indices, that are often faster:

 idx = A < 5;

In both cases you get the indexed numbers using

 A(idx)

[cgo]

perfect. thanks