R help - Apr 2008 - Load the shared object/DLL

Dear All,

I have written a function in c (in a file named 'a.c') as follows,

void convolve(double *a, int *na, double *b, int *nb, double *ab)
{
 int i, j, nab = *na + *nb - 1;

 for(i = 0; i < nab; i++)
    ab[i] = 0.0;
 for(i = 0; i < *na; i++)
    for(j = 0; j < *nb; j++)
       ab[i + j] += a[i] * b[j];
}

Then, I created a shared file in the Windows,

 R CMD SHLIB -d -o a.dll a.c

Every thing is OK now.

I changed the working directory of the R environment to the directory
containing the a.dll.
I enter two commands in the R console,
> dyn.load("a.dll")
> is.loaded("a")
[1] FALSE

The question is that, why was the "a.dll" failed to be loaded in the R
enviroment? Which step resuted in this problem?

Any suggestion was welcome.

G. Ding

	[[alternative HTML version deleted]]

On Wed, 16 Apr 2008, Guohui Ding wrote:
> Dear All,
>
> I have written a function in c (in a file named 'a.c') as follows,
*PLEASE* don't claim credit for the work of others (in this case it is me 
that you owe the apology and retraction to).  That is from 'S
Programming'
p. 126, and 'Writing R Extensions'.
> void convolve(double *a, int *na, double *b, int *nb, double *ab)
> {
> int i, j, nab = *na + *nb - 1;
>
> for(i = 0; i < nab; i++)
>    ab[i] = 0.0;
> for(i = 0; i < *na; i++)
>    for(j = 0; j < *nb; j++)
>       ab[i + j] += a[i] * b[j];
> }
>
> Then, I created a shared file in the Windows,
>
> R CMD SHLIB -d -o a.dll a.c
>
> Every thing is OK now.
>
> I changed the working directory of the R environment to the directory
> containing the a.dll.
> I enter two commands in the R console,
>
>> dyn.load("a.dll")
>> is.loaded("a")
> [1] FALSE
>
> The question is that, why was the "a.dll" failed to be loaded in
the R
> enviroment? Which step resuted in this problem?
It did not fail.  is.loaded("a") looks for entry point "a",
and you have
"convolve".
> Any suggestion was welcome.
Do note that posting guide said about where to post non-R programming 
questions.
>
> G. Ding
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
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> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595