R Under development (unstable) (2023-12-07 r85661 ucrt) -- "Unsuffered Consequences"
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> ## from Eric Weese
> library(bbmle)
Loading required package: stats4
> f <- function(x=2,a=1) x^2 - a
> f.g <- function(x,a) 2*x
> f.g2 <- function(x,a) c(2*x,0)
> options(digits=3)
> m1 <- mle2(f,fixed=list(a=1))
> m2 <- mle2(f,gr=f.g,fixed=list(a=1))
> m3 <- mle2(f,gr=f.g2,fixed=list(a=1))
> stopifnot(all.equal(coef(m1),coef(m2)))
> stopifnot(all.equal(coef(m1),coef(m3)))
> tt <- function(x) x@details$hessian
> stopifnot(all.equal(tt(m1),tt(m2),tolerance=1e-6))
> stopifnot(all.equal(tt(m1),tt(m3),tolerance=1e-6))
> 
> proc.time()
   user  system elapsed 
   1.28    0.15    1.42