Instead of NaN's, I get the error message: Error in eval(expr, envir, enclos) : object 'z' not found. The reason you get the NaN's is, because you defined z in your global environment. The deltaMethod doesn't find the z defined in your function. I don't know why or how to fix this. Somebody with more R experience could probably do this. But if you look at the source code of deltaMethod you can solve the problem in your specific case with these function.
deltaMethod2 <- function(object, g, vcov., z, ...){ if (!is.character(g)) stop("The argument 'g' must be a character string") if ((car:::exists.method("coef", object, default = FALSE) || (!is.atomic(object) && !is.null(object$coefficients))) && car:::exists.method("vcov", object, default = FALSE)) { if (missing(vcov.)) vcov. <- vcov(object) object <- coef(object) } para <- object para.names <- names(para) g <- parse(text = g) q <- length(para) for (i in 1:q) { assign(names(para)[i], para[i]) } est <- eval(g) names(est) <- NULL gd <- rep(0, q) for (i in 1:q) { gd[i] <- eval(D(g, names(para)[i])) } se.est <- as.vector(sqrt(t(gd) %*% vcov. %*% gd)) data.frame(Estimate = est, SE = se.est) } deltaSE <- function(mod, x){ mod.SE <- list() for(i in 1:length(x)){ z <- x[i] mod.SE[[i]] <- deltaMethod2(mod, g="(m0^(1/lambda) - (z * m0/t0)^(1/lambda))^lambda", z=z)$SE } mod.SE } deltaSE(nlls, xVal) -----Original Message----- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of PatGauthier Sent: Freitag, 22. März 2013 13:54 To: r-help@r-project.org Subject: Re: [R] Trouble embedding functions (e.g., deltaMethod) in other functions Ah Yes, good point. However, it still does not correct the situation. I still get NaN's. -- View this message in context: http://r.789695.n4.nabble.com/Trouble-embedding-functions-e-g-deltaMethod-in-other-functions-tp4662178p4662187.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. ______________________________________________ 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.