Question

I want to find the n-th smallest element for each row in a matrix.

Example:

n = 2
M = [1, 2, 3; 4, 5, 6; 7, 8 9]
Result = [2, 5, 8]

Answer 1

First sort the matrix by the second dimension (i.e. sort every row in ascending order):

n = 2
M = [1, 2, 3; 4, 5, 6; 7, 8 9]

M_SORTED = sort(M,2)
M_SORTED =
     1     2     3
     4     5     6
     7     8     9

The n-th column of the matrix will contain the result:

RESULT = M_SORTED(:, n)
RESULT = 
     2
     5
     8