Swapping rows and columns

Question

I need a MATLAB function that will swap 2 rows or 2 Columns with each other in a matrix of arbitrary size.

Answer 1

Say you take the matrix

>> A = magic(4)
A =
    16     2     3    13
     5    11    10     8
     9     7     6    12
     4    14    15     1

If you want to swap, say, columns 3 and 1, you write

>>A(:,[1 3]) = A(:,[3 1])

A =
     3     2    16    13
    10    11     5     8
     6     7     9    12
    15    14     4     1

The same works for swapping rows (i.e. A([4 2],:) = A([2 4],:) to swap rows 2 and 4).