[Rcpp-devel] Using complex numbers in a C program called by R

Pierre Lafaye de Micheaux lafaye at dms.umontreal.ca
Sun Jan 3 21:36:03 CET 2016

Dear all,

This email comes after a discussion on the R-pkg-devel mailing list:

My purpose was to be able, in two of my packages, to use complex numbers 
(create some, addition, multiplication, division, modulus, etc)
directly in a C code that is called from R (using the .C interface).
Note that these complex numbers might not come from R but could be 
created and used directly in my C code, that will then output (via 
real (I mean double) values back to R (via the .C interface). I could 
also send from R these complex numbers via the .C interface.

A very simple example of such a function called from R via the .C 
interface could be the following:

#include <R.h>
#include "Rmath.h"
extern "C" {
void Cfunc(complex double *var) {
     double _Complex z = 1.0 + 2.0 * _Complex_I;
     var[0] = z + exp(var[0]);

I could call this function from R as follows:

No problem so far when I use such a function in a package that is 
compiled under Linux. But this will not work under windows (see the 
on the R-pkg-devel list). So what I did to make everything work under 
Windows also was to include in the src/ directory of my package the 
source files
from the RcppFaddeeva package. Then I would modify the function above as 

#include <R.h>
#include "Rmath.h"
#include "libraries/callFaddeeva.cpp"
#include "libraries/Faddeeva.cpp"
#include "libraries/RcppExports.cpp"
extern "C" {
void Cfunc(complex double *var) {
     cmplx z = C(1.0, 2.0);
     var[0] = z + cexp(var[0]);

Maybe there is a way not to include all the Faddeeva source files in my 
packages? But I do not know how to do it.

Best regards,

Pierre L.

Pierre Lafaye de Micheaux

Adresse courrier:
Université de Montréal
Pavillon André-Aisenstadt
Département de Mathématiques et Statistique
CP 6128 Succursale Centre-ville
Montréal Qc H3C 3J7

Adresse physique:
Département de Mathématiques et Statistique
Bureau 4249, Pavillon André-Aisenstadt
2920, chemin de la Tour
Montréal, Québec H3T 1J4

Tél.: (00-1) 514-343-6607 / Fax: (00-1) 514-343-5700
lafaye at dms.umontreal.ca

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