dimension mismatch error in matrix.?

 A = [1 2 3;3 4 5;5 6 7]
 B = [4 5 6;6 7 8;7 8 9]
 For I = 1:3
 C(:,I) = [A(:,2*I-1) B(:,2*I)]
 end

I want C as a matrix whose odd columns will be from A and even columns will be from B. So that output matrix will be 3x6 But this program shows dimension mismatch error.

Answer 1

[Matt J]

 C(:, 2:2:2*size(B,2))=B;
 C(:, 1:2:end)=A;