Sorry folks I posted the code with a bug in approach 2. aarrrhh. it should have been...
## Approach 2: loop on k2 output2 = matrix(0,nrow=n,ncol=k2) pt2 = proc.time(for (i in 1:k2) output2[,i] = rowSums( m1*(m2[,rep(i,3)]) )) > I haven't seen any other response yet (after 8 hours!) but doesn't: > rowSums(m1)*m2 > do what you want? > > HTH > Ray Brownrigg ... which is a very long winded way to do exactly what Ray did very easily. Thanks for the pointer Ray. Dave ______________________________________________ [email protected] 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.
