Dear R, I have three matrices like this K: pp-by-pp commutation matrix, I: p-by-p diagonal matrix, X: p-by-q dense matrix, and I wish to calculate K(IoX) where `o' denotes Kronecker product. Can you give me any suggestion to speed it up when `p' and `q' are large? Thanks in advance. Feng -- Feng Li Department of Statistics Stockholm University 106 91 Stockholm, Sweden http://feng.li/ [[alternative HTML version deleted]]