[R] replicating C example from the Extensions Manual problem

[Joshua Wiley]

Hi Erin,

If you are just starting with including compiled code, I would highly
recommend the Rcpp + inline packages.  I attached a small example of
how it works, but basically you get to inline C++ code in R files.

Cheers,

Josh

P.S. I wrote this snippet awhile ago when I did not know much about
C++ so that code is sloppy, but it demonstrates the point and I am
short on time right now.

On Wed, Mar 14, 2012 at 11:03 PM, Erin Hodgess <erinm.hodgess at gmail.com> wrote:
> Dear R People:
>
> Here is something that I am sure is very simple.  I'm just trying to
> re-create the C convolution example in the Extensions manual.  Here is
> the subroutine:
>
> void convolve(double *a, int *na, double *b, int *nb, double *ab)
> {
> R_len_t 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];
> }
>
> And here are the results from trying to compile:
>
> erin at ubuntu:~$ R CMD SHLIB convolve.c
> gcc -std=gnu99 -I/usr/share/R/include      -fpic  -O3 -pipe  -g -c
> convolve.c -o convolve.o
> convolve.c: In function ‘convolve’:
> convolve.c:3:1: error: unknown type name ‘R_len_t’
> make: *** [convolve.o] Error 1
>
>
> What is wrong, please?
>
> This is on Ubuntu 11.10 with R-2.14.2.  I'm sure that it's totally goofy.
>
> Thanks,
> Erin
>
>
>
> --
> Erin Hodgess
> Associate Professor
> Department of Computer and Mathematical Sciences
> University of Houston - Downtown
> mailto: erinm.hodgess at gmail.com
>
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-- 
Joshua Wiley
Ph.D. Student, Health Psychology
Programmer Analyst II, Statistical Consulting Group
University of California, Los Angeles
https://joshuawiley.com/