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

[Baptiste Auguie]

Hi,

Just to clarify: did you include files from RcppFaddeeva because you need
some of its functionality (special complex error functions), or was it only
a workaround to get access to complex numbers? In the latter case, I
recommend you try making a minimal Rcpp package to see how easy it is to
interface with C+ functions, and that way you will only have relevant
header files included.

Best,

baptiste



On 4 January 2016 at 09:36, Pierre Lafaye de Micheaux <
lafaye at dms.umontreal.ca> wrote:

> Dear all,
>
> This email comes after a discussion on the R-pkg-devel mailing list:
> https://stat.ethz.ch/pipermail/r-package-devel/2016q1/000627.html
>
> 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 pointers)
> 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]);
> return;
> }}
>
> I could call this function from R as follows:
> .C(1i)
>
> 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 discussion
> 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
> follows:
>
> #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]);
> return;
> }}
>
> 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
> CANADA
>
> Adresse physique:
> Département de Mathématiques et Statistique
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>
> Tél.: (00-1) 514-343-6607 / Fax: (00-1) 514-343-5700
> lafaye at dms.umontreal.ca
> http://www.biostatisticien.eu
>
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