flip certain columns in matrix

hey all i need to flip every nth column in a matrix. ie. if i have matrix A=[1 2 3;4 5 6;7 8 9] i need it to become A=[1 8 3;4 5 6;7 2 9] any suggestions?

Answer 1

[Adam]

n = 2;  
colIdx = 2:n:size(A,2);
A(:,colIdx) = flip( A(:,colIdx) )

assuming you want to flip even columns (in the case of n = 2). Obviously for odd colums just change the first line to:

colIdx = 1:n:size(A,2);

[john creighton]

Thanks Adam. works perfectly :)

Answer 2

[raja bala]

         A(:,[2]) = flip (A(:,[2]))

[Adam]

This flips the 2nd column only, as does

A(:,2) = flip (A(:,2))

without the square brackets.