[R] dyn.load and c-function

[Peter Dalgaard BSA]

"Jeff D. Hamann" <jeff_hamann at hamanndonald.com> writes:

> tf2 <- function( a, b, c )
>   .C("testfunc2",
>      as.integer(a),
>      as.double(b),
>      as.integer(c),
>      as.double(d) )[[4]]
> 
> I get an "Object d not found" error...
> 
> how would I write the R part so that I can call my function the way I want
> to?

Your C function assumes that d (or "result" as you call it on the
other side) exists with the relevant length. So you need to create it:

tf2 <- function( a, b, c ){
    d <- double(length(a))
   .C("testfunc2",
      as.integer(a),
      as.double(b),
      as.integer(c),
      d)[[4]]
}

or just 

tf2 <- function( a, b, c )
   .C("testfunc2",
      as.integer(a),
      as.double(b),
      as.integer(c),
      double(length(a)))[[4]]


-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907
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