b<-rep(0,n-11) for(i in 0:(11-10)) b<-b+a[(i+1):(n-11+i)] i don't know what does "rep" mean and for-loop! -- View this message in context: http://r.789695.n4.nabble.com/please-help-for-mgcv-package-tp3614485p3615861.html Sent from the R help mailing list archive at Nabble.com.