I meant "sparse matrix", sorry for the typo. Feng
On Sat, Jan 29, 2011 at 7:02 PM, Feng Li <m...@feng.li> wrote: > Dear R, > > I have a simple question concerning with a special case of sparse matrix > multiplications. Say A is a 200-by-10000 dense matrix. B is a 10000-by-10000 > block- diagonal matrix, and each diagonal block B_i is 100-by-100. The usual > way I did A%*%B will take about 30 seconds which is to time consuming > because I have to do this thousands of times. I also tried to partition A > into 100 small blocks and use mapply function to multiply by each B_i, but > that is even slower. > > I am wondering if there is an efficient way to perform this type of > multiplication with R? > > Thanks in advance! > > Feng > > -- > Feng Li > Department of Statistics > Stockholm University > 106 91 Stockholm, Sweden > http://feng.li/ > > -- Feng Li Department of Statistics Stockholm University 106 91 Stockholm, Sweden http://feng.li/ [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
