On Fri, 26 Sep 2003, Axel Benz wrote: > Hi, > I am about to write functions for multivariate kernel densitiy estimation > with mixed categorical and continuous date (accoring to Jeff Racine and Qi > Li), and the leave-one-out window esitmation needs a lot of computation. > I am now optimizing the code performance and therefore fhe following > questions: > > As R uses call-by-value for functions, is it computational expensive to pass > large matrices in function arguments?
No, as long as they are not modified. R doesn't make actual copies if it knows they aren't needed, it just creates a reference to the original object. > (i.e. are they really copied and does this need much computing time?) Is it > maybe better to work with locally visible variables and nested functions in > the optimized code? It probably won't make a detectable difference. Looking up a variable is microscopically quicker if it is local (eg passed as a parameter), but you need fairly extreme cases for this to be noticeable. -thomas Thomas Lumley Assoc. Professor, Biostatistics [EMAIL PROTECTED] University of Washington, Seattle ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help