Hi all,

Would be great if you could help me get my head around the "further
arguemnts" in the optim function. Let's say we have f and g as shown:

f<-function(x,a,b){(x-a)^2+b}

optim(100,fn=f,gr=NULL,2,5) #the NULL is annoying

g<-function(x,a){2*(x-a)} optim(100,fn=f,gr=g,2,5)


1. How does optim know that 2,5 both go into f whereas g only accepts the
first of those arguments. WHAT IF for some random reason I wanted there to
be no common parameters, what then? so for example the input for g to be 3
s.t. f(x,2,5) and g(x,3)

2. Is there a way for me to skip writing gr=NULL the first time I implement
this? Its quite important for me as I want to implement optimx where the
"further arguments" are the last ones, and I do not want to go setting each
parameter to some sort of default. basically I want to say:

optim(100,fn=f,further_args=c(2,5))

Thanks in advance,
Sachin

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