## =======================================================================
## the banana function
## =======================================================================
fun <- function(x) 100*(x[2] - x[1]^2)^2 + (1 - x[1])^2
mm <- nlm(fun, p = c(0, 0))$estimate
(Hes <- hessian(fun, mm))
# can also be estimated by nlm(fun, p=c(0,0), hessian=TRUE)
solve(Hes) # estimate of parameter uncertainty
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