Sorts a given matrix by a specific column while retain the elements in each row.
sort_mat(x, col)The matrix sorted by values in the specified column.
A matrix to sort
A int that indicates the column the matrix should sort by.
The functional difference between armadillo's sort() and sort_mat() is straight forward. sort() will sort each column without respect to the rows. Using sort_matrix will sort only 1 column and retain the other elements to be in the same row.