[Rd] names treatment in optim()

Christophe Dutang dutangc at gmail.com
Thu Sep 17 13:04:19 CEST 2015

Dear both,

I have found that names are not treated in the same way in optim() depending on the optimization method (argument method). 

The example below shows the difference between the Brent method and the L-BFGS-B method.

f <- function(x){ y <- x^2;names(y) <-"f(x)";y}
optim(10, f, method="Brent", lower=-1, upper=10)$value
optim(10, f, method="L-BFGS-B", lower=-1, upper=10)$value

z <- 10
names(z) <- "x"
optim(z, f, method="Brent", lower=-1, upper=10)$par
optim(z, f, method="L-BFGS-B", lower=-1, upper=10)$par

Do you obtain the same behavior? would you consider interesting to have the names passed to the components value and par?

I’m using R version 3.2.2 (2015-08-14)
Platform: x86_64-apple-darwin13.4.0 (64-bit)
Running under: OS X 10.10.5 (Yosemite)

[1] fr_FR.UTF-8/fr_FR.UTF-8/fr_FR.UTF-8/C/fr_FR.UTF-8/fr_FR.UTF-8

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base   

Kind regards, Christophe

Christophe Dutang
LMM, UdM, Le Mans, France
web: http://dutangc.free.fr <http://dutangc.free.fr/>

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