How to vectorize row-wise diagonalization of a matrix

Question

I have an n-by-m matrix that I want to convert to a mn-by-m matrix, with each m-by-m block of the result containing the diagonal of each row.

For example, if the input i

Answer 1

For a vectorized way to do this, create the linear indices of the diagonal elements into the resulting matrix, and assign directly.

%# create some input data
inArray = [10 11;12 13;14 15];

%# make the index array
[nr,nc]=size(inArray);

idxArray = reshape(1:nr*nc,nc,nr)';
idxArray = bsxfun(@plus,idxArray,0:nr*nc:nr*nc^2-1);

%# create output
out = zeros(nr*nc,nc);
out(idxArray) = inArray(:);

out =

    10     0
     0    11
    12     0
     0    13
    14     0
     0    15