Re: [R] Cannot call R's ISNAN() from a C code in >1.7 versions.

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From: Prof Brian Ripley (
Date: Mon 24 May 2004 - 16:40:42 EST

Message-id: <Pine.LNX.4.44.0405240729290.14723-100000@gannet.stats>

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,        
Professor of Applied Statistics,
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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