Finding the second smallest value in each column of an array?

This is probably very simple. I have an array of size, say 10 by 30. In each column, there is definitely an element with a value of 0, the rest of the nine: values > 0. Now, I want a row vector containing the second smallest values from each column of the original array.

Any idea? If I were to use min(array), I would get a row vector with all 0's. Maybe I have to use bubble sorting?

[Jason]

All good answers. I am finding it hard to pick and accept one. Someone help me?

Answer 1

[Jan]

Sorting is a good idea:

X = rand(10, 10);
Xs = sort(X);
min2nd = Xs(2, :);

This is not very efficient, but most likely the fastest Matlab method.

Answer 2

[Walter Roberson]

t = array;
t(t==0) = inf;
min(t)

Answer 3

[Pierre]

You could simply take advantage of Bruno Luong's Min/Max selection implemented in MEX. AFAIK they implement Hoare's selection algorithm (which is a deviation of quicksort).