how to multiply a number in even rows of matrix?

I have: output2=-1*ones(input1,input4), how do i make all the even columns be 2? Thanks

Task: output2 is an (input1) × input4 matrix where the entries of all the odd columns are all -1 and the entries of all the even columns are all 2’s.

Answer 1

[Akira Agata]

Please try the following:

output2(:,2:2:end) = 2;