R-loop-killers: I'm looking for a hint to remove the loops from this little piece of code. Since most of the of computing I deal with is very "loop-centric", it's often difficult for me to translate index-based code into loop-free code. Does anyone have any hints for speeding this up? The actuals is a data.frame object and the resids is a simple matrix... cb <- cov( rbind( actuals$tvolh, resids[,5] ) ) covb <- 0 for( i in 1:nrow( actuals ) ) { for( j in 2:nrow( actuals ) ) { covb <- covb + actuals[i,]$ha * block.acts[j,]$ha * cb[i,j] } } thanks, Jeff. -- Forest Informatics, Inc. PO Box 1421 Corvallis, Oregon 97339-1421