MATLAB: What is the elegent way to replace every Nth column in a matrix with another column

Question

It looks easy with a for loop, but I am a beginner and was told to try and avoid for loops…

I though abot something that looks like A(;,n:n:end) but I get a "dimensions mismatch error"

Thank you

Answer 1

           B = randn(10,10);
           % replace every 3rd column with x
           x = randn(10,1);
           N = 3;
           indices = 1:N:size(B,2);
           x = repmat(x,1,length(indices));
           B(:,indices) = x;

Probably you are trying to replace a matrix which you get with A(:,1:n:end) with a vector. The sizes have to match.