Nothing
powell <- function(par, fn, control = powell.control(),
check.hessian = TRUE, ...) {
dots <- list(...)
expr <- Quote(fn(..par..))
if(length(dots)) {
expr[names(dots)] <- dots
expr <- as.call(expr)
}
env <- new.env(list(fn = fn))
control <- do.call("powell.control", control)
any.na <- sapply(lapply(control, is.na), sum)
if(any(is.na(par)) || any(any.na > 0))
stop("missing values not allowed in call")
n <- length(par)
if(length(control$parscale) != n) {
if(length(control$parscale) == 1)
control$parscale <- rep(control$parscale, n)
else
stop("control$parscale must be determined for all values in \"par\"")
}
ret <- .Call("R_UObyQA", as.double(par), expr, control, env, PACKAGE = "powell")
names(ret) <- c("par", "value", "counts", "hessian")
npar <- length(ret$par)
ret$hessian <- matrix(ret$hessian, npar, npar)
if(!is.null(parnm <- names(par))) {
names(ret$par) <- parnm
dimnames(ret$hessian) <- list(parnm, parnm)
}
if(check.hessian) {
ret$eigen.hessian <- eigen(ret$hessian, symmetric = TRUE)
ev <- ret$eigen.hessian$values
if(!all(ev >= -.Machine$double.eps^0.5 * abs(ev[1])))
warning(ret$message <- "Hessian is not positive definite.")
}
names(ret$counts) <- "function"
ret$convergence <- ifelse(control$maxit == ret$counts, 1, 0)
ret$control <- control
ret$call <- match.call()
ret
}
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