https://github.com/cran/pracma
Tip revision: 708a2ad382a163d1eef5af0665e3ae2aad200ced authored by HwB on 21 March 2013, 00:00:00 UTC
version 1.4.5
version 1.4.5
Tip revision: 708a2ad
taylor.R
##
## t a y l o r . R Taylor Series Approximation
##
taylor <- function(f, x0, n = 4, ...) {
if (!is.numeric(x0))
stop("Argument 'x0' must be a numeric value or vector.")
if (!is.numeric(n) || floor(n) != ceil(n) || length(n) != 1)
stop("Order 'n' must be an scalar integer between 1 and 8.")
fun <- match.fun(f)
f <- function(x) fun(x, ...)
if (n > 8) {
# n <- 8
warning("Order 'n' is too high; should not be greater than 'n=8'.")
} else if (n <= 0) {
n <- 4
warning("Order 'n' is too low; will be reset to the default 'n=4'.")
}
T <- f(x0)
for (i in 1:n) {
T <- polyadd(T, fderiv(f, x0, i)/fact(i) * polypow(c(1, -x0), i))
}
return(T)
}