Most certainly you can speed it up: X <- exp(-abs(row(X) - col(X)) / (3*b)) diag(X) <- a
should do what you want. This is called 'vectorization' and is discussed lots of places -- for instance, in the two documents mentioned below in my signature. On 01/08/2011 19:12, monk wrote:
dear all, i have a quite simple question, i want to fill up a Matrix like done in the following function, but the performance is very bad for large dimensions is there a way to do this like with apply or something similar? makeMatrix<- function(a, b,dim) { X=matrix(0,ncol=dim,nrow=dim) for (i in c(1:dim)){ for (j in c(1:dim)) { if (i==j) {X[i,j]<-a} else { X[i,j]<- exp(( -1*abs(i-j))/(3*b)) } } } X } -- View this message in context: http://r.789695.n4.nabble.com/fill-Matrix-quicker-tp3710428p3710428.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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.
-- Patrick Burns pbu...@pburns.seanet.com twitter: @portfolioprobe http://www.portfolioprobe.com/blog http://www.burns-stat.com (home of 'Some hints for the R beginner' and 'The R Inferno') ______________________________________________ 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.