[R] Rcpp, dyn.load and C++ problems

[Martin Møller Skarbiniks Pedersen]

On 3 December 2017 at 05:23, Eric Berger <ericjberger at gmail.com> wrote:

> .Call("compute_values_cpp")
> Also, if you were passing arguments to the C++ function you would need to
> declare the function differently.
> Do a search on "Rcpp calling C++ functions from R"
>
>
Hi,
  It is still not working.
  $ ./compile.sh
g++  -I/usr/include/R/ -DNDEBUG   -D_FORTIFY_SOURCE=2
-I/home/tusk/R/x86_64-pc-linux-gnu-library/3.4/Rcpp/include -fpic
-march=x86-64 -mtune=generic -O2 -pipe -fstack-protector-strong -fno-plt
-c logistic_map.cpp -o logistic_map.o
g++ -shared -L/usr/lib64/R/lib
-Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now -o logistic_map.so
logistic_map.o -L/usr/lib64/R/lib -lR

$ readelf -Ws logistic_map.so  | grep -i comp
    89: 0000000000002a50  2356 FUNC    GLOBAL DEFAULT    9
_Z18compute_values_cppidid
   141: 0000000000002a50  2356 FUNC    GLOBAL DEFAULT    9
_Z18compute_values_cppidid

$ R
R> dyn.load("logistic_map.so")
R> .Call("compute_values_cpp")
Error in .Call("compute_values_cpp") :
  C symbol name "compute_values_cpp" not in load table

Hmm.



> HTH,
> Eric
>
>
> On Sun, Dec 3, 2017 at 3:06 AM, Martin Møller Skarbiniks Pedersen <
> traxplayer at gmail.com> wrote:
>
>> Hi,
>>
>>   I have written a small C++ function and compile it.
>>   However in R I can't see the function I have defined in C++.
>>   I have read some web-pages about Rcpp and C++ but it is a bit confusion
>> for me.
>>
>> Anyway,
>>   This is the C++-code:
>>
>> #include <Rcpp.h>
>> using namespace Rcpp;
>>
>> // [[Rcpp::export]]
>> List compute_values_cpp(int totalPoints = 1e5, double angle_increment =
>> 0.01, int radius = 400, double grow = 3.64) {
>>   double xn = 0.5;
>>   double angle = 0.1;
>>   double xn_plus_one, yn_plus_one;
>>   NumericVector x(totalPoints);
>>   NumericVector y(totalPoints);
>>
>>   for (int i=0; i<totalPoints; i++) {
>>     xn_plus_one = xn*cos(angle)*radius;
>>     yn_plus_one = xn*sin(angle)*radius;
>>     angle += angle_increment;
>>     xn = grow*xn*(1-xn);
>>     x[i] = xn_plus_one;
>>     y[i] = yn_plus_one;
>>   }
>>   return List::create(Rcpp::Named("x") = x, Rcpp::Named("y") = y);
>> }
>>
>> And I compile it like this:
>> PKG_CXXFLAGS=$(Rscript -e 'Rcpp:::CxxFlags()') \
>> PKG_LIBS=$(Rscript -e 'Rcpp:::LdFlags()')  \
>> R CMD SHLIB logistic_map.cpp
>> without problems and I get a logistic_map.so file as expected.
>>
>> However in R:
>> R> dyn.load("logistic_map.so")
>> R> compute_values_cpp()
>> Error in compute_values_cpp() :
>>   could not find function "compute_values_cpp"
>>
>> Please advise,
>>   What piece of the puzzle is missing?
>>
>> Regards
>> Martin M. S. Pedersen
>>
>>         [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posti
>> ng-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
>


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