I am trying to write a dynamic linked library for R, in Pascal. (This
is to speed up the execution of a simulation that I am running in R.)
I know Pascal might not be the perfect language for this (C or Fortran
being more natural), but from what I have read I think it should
work. Though I should point out that I am a neophyte when it comes to
DLLs.
From R I want to hand a function in the library a two-dimensional
matrix, operate on the matrix, and hand back a 2-d matrix.
I have no problem creating the library and loading it using dyn.load()
I have written an R wrapper for the function.
When I do something simple using scalars (integers) everything works
fine, or so it seems at least.
However, when I try to use a vector as an argument to the function,
two things happen:
R becomes very unstable;
the function only operates on the first 3 elements of the vector (say
if the vector has 5 elements).
Anyone have experience with this sort of thing?
Thanks,
Robin Cowan
Sample below:
This one works fine:
library Test1Lib;
type
pA=^integer;
procedure simple(x:pA); cdecl;
var i1,i2:integer;
begin
x^:=x^*2;
end;
exports simple;
begin
end.
This one does not:
library Test2Lib;
type
array1=array[1..5] of integer;
pA=^array1;
procedure simpleArray(x:pA); cdecl;
var i1:integer;
begin
for i1:=1 to 5 do
x^[i1]:=x^[i1]*2;
end;
exports simpleArray;
begin
end.
Here is the wrapper I use:
MySimple <- function(x)
{
ans <- .C("simple",as.integer(x)) # or simpleArray in the second case
ans[[1]]
}
Here is what I get:
> x<-c(1,2,3,4,5)
> MySimple(x)
[1] 2 4 6 4 5
The University of Maastricht has changed its name and mail servers. My
email address is now r.co...@maastrichtuniversity.nl.
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