search for: expr13

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2004 May 14
2
NLME model question
...of growth. these parameters are from a logistic (r & k) . i have attempted to construct a self starting routine for nlme ie: SSGrowth_function(x, r, k) { .expr2 <- (k - 100000)/100000 .expr5 <- exp(((r * -1) * x)) .expr7 <- 1 + (.expr2 * .expr5) .expr13 <- .expr7^2 .value <- k/.expr7 .actualArgs <- match.call()[c("r", "k")] if(all(unlist(lapply(as.list(.actualArgs), is.name)))) { .grad <- array(0, c(length(.value), 2), list(NULL, c("r", "k")))...
2001 May 01
0
SSfpl self-start sometimes fails... workaround proposed
...se a modified self-start function for SSfpl that remedy to this: --------------------------------------- fpl <- function (input, A, B, xmid, scal) { .expr1 <- B - A .expr2 <- xmid - input .expr4 <- exp((.expr2/scal)) .expr5 <- 1 + .expr4 .expr8 <- 1/.expr5 .expr13 <- .expr5^2 .value <- A + (.expr1/.expr5) .actualArgs <- as.list(match.call()[c("A", "B", "xmid", "scal")]) if (all(unlist(lapply(.actualArgs, is.name)))) { .grad <- array(0, c(length(.value), 4), list(NULL, c("A", &q...