[R] How to use result of approxfun in a package?

[Steve Buyske]

I am working on a project where we start with start with 2 long,  
equal-length vectors, massage them in various ways, and end up with a  
function mapping one interval to another. I'll call that function  
"f1." The last step in R is to generate f1 as the value of the  
approxfun function. I would like to put f1 into a package, but  
without having the package redo the creation of function f1. The  
value of approxfun is a function; for example, I have

 > f1
function (v)
.C("R_approx", as.double(x), as.double(y), as.integer(n), xout =  
as.double(v),
     as.integer(length(v)), as.integer(method), as.double(yleft),
     as.double(yright), as.double(f), NAOK = TRUE, PACKAGE = "base") 
$xout
<environment: 0x17719324>

I don't really understand how this is stored, and in particular, how  
I should handle it so as to include the function f1 in a package. I  
would like the users to be able to load the package and use f1  
directly, rather than re-generate it using approxfun.

Thanks,
Steve
---
Steve Buyske (rhymes with "nice key")
Associate Research Professor
Department of Statistics & Biostatistics
Rutgers University
Hill Center, 110 Frelinghuysen Rd
Piscataway, NJ 08854
buyske at stat.rutgers.edu