Here is one way. To have a vectorized version you need to redefine 't0', though
t0 <- function(x) {1} t1 <- function(x) {x} t2 <- function(x) {x^2} t3 <- function(x) {x^3} ttt <- list(t0,t1,t2,t3) rrr <- function(x) sum(sapply(seq(along=ttt), function(i) ttt[[i]](x))) ## vectorized version ttt[[1]] <- t0 <- function(x) rep(1, length(x)) rrr2 <- function(x) rowSums(sapply(seq(along=ttt), function(i) ttt[[i]](x))) Hope this helps, Giovanni > Date: Fri, 20 Oct 2006 15:19:06 +0100 > From: James Foadi <[EMAIL PROTECTED]> > Sender: [EMAIL PROTECTED] > Precedence: list > User-Agent: KMail/1.9.4 > > Dear all, > I have looked for an answer for a couple of days, but can't come with any > solution. > > I have a set of functions, say: > > > t0 <- function(x) {1} > > t1 <- function(x) {x} > > t2 <- function(x) {x^2} > > t3 <- function(x) {x^3} > > I would like to find a way to add up the previous 4 functions and obtain a > new > function: > > > rrr <- function(x) {1+x+x^2+x^3} > > without, actually, having to write it in the previous form (I could have > cases > with hundreds of functions). I thought that perhaps I could first define a > list of functions: > > > ttt <- list(t0,t1,t2,t3) > > and then I could use something like "sum", to add up all the elements of the > list and obtain another function. I've tried: > > > rrr <- function(x) {sum(ttt)} > > but it does not work. > > Any help with this is greatly appreciated. > > Cheers, > > james > -- > Dr James Foadi > Department of Physics > University of York > York YO10 5DD > > email: [EMAIL PROTECTED] > web page: http://www-users.york.ac.uk/~jf117 > Tel: 0044 1904 434622 > Mobile: 0044 7740 678548 > > ______________________________________________ > R-help@stat.math.ethz.ch 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. > > -- __________________________________________________ [ ] [ Giovanni Petris [EMAIL PROTECTED] ] [ Department of Mathematical Sciences ] [ University of Arkansas - Fayetteville, AR 72701 ] [ Ph: (479) 575-6324, 575-8630 (fax) ] [ http://definetti.uark.edu/~gpetris/ ] [__________________________________________________] ______________________________________________ R-help@stat.math.ethz.ch 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.