R help - May 2004 - Cannot call R's ISNAN() from a C code in >1.7 versions.

Dear R users,

Have you experienced any difficulty in calling R's ISNAN() from a C
code? I have C codes including ISNAN() calls and they worked well until
I upgraded my R from 1.7 to later versions. When I tried to compile the
codes in the version 1.8 and 1.9, I got error messages like this:

   test.obj : error LNK2001: unresolved external symbol _isnan
   .\testR.dll : fatal error LNK1120: 1 unresolved externals
   NMAKE : fatal error U1077: 'link.exe' : return code '0x460'
   Stop.

I checked "Writing R Extensions" and did not find any changes in the
API
entry point for ISNAN in the later versions. Could any one enlighten me
on why _isnan cannot be resolved? The compiler I used is MSVC++ 6.0 and
the platform is WinXP. Many thanks.

Paul.

First, there are no versions 1.7, 1.8 and 1.9.

Was your version of R compiled against MSVC++ 6.0?  The binary on CRAN was
not, and binaries for different versions of R were compiled with different
versions of MinGW.  The entry point isnan is part of the statically linked
runtime on modern MinGW.

MSVC++ 6.0 does supply _isnan (as it really should as it is part of the
C99 ISO standard), and you need to link against it appropriately.  Hint:
it may have an extra underline, since it seems it is known to C as _isnan.
You may need to add

#undef ISNAN
#define ISNAN(x) _isnan(x)


We don't support adding extensions to R using a different compiler to the 
one used to build R.  Changes already made for future releases of R will 
make this less likely to work in R 2.0.x.


On Mon, 24 May 2004, Paul Y. Peng wrote:
> Dear R users,
> 
> Have you experienced any difficulty in calling R's ISNAN() from a C
> code? I have C codes including ISNAN() calls and they worked well until
> I upgraded my R from 1.7 to later versions. When I tried to compile the
> codes in the version 1.8 and 1.9, I got error messages like this:
> 
>    test.obj : error LNK2001: unresolved external symbol _isnan
>    .\testR.dll : fatal error LNK1120: 1 unresolved externals
>    NMAKE : fatal error U1077: 'link.exe' : return code
'0x460'
>    Stop.
> 
> I checked "Writing R Extensions" and did not find any changes in
the API
> entry point for ISNAN in the later versions. Could any one enlighten me
> on why _isnan cannot be resolved? The compiler I used is MSVC++ 6.0 and
> the platform is WinXP. Many thanks.
-- 
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