On Feb 10, 2008 12:55 PM, Jim Razmus <[EMAIL PROTECTED]> wrote: > * Chris Kuethe <[EMAIL PROTECTED]> [080210 12:34]: > > On Feb 10, 2008 8:31 AM, Jim Razmus <[EMAIL PROTECTED]> wrote: > > > I'm trying to compile a program that uses NAN. It includes math.h which > > > I'm told C99 says should define it. I've grepped the entire source tree > > > and read up on man 3 math and man 3 isinf. Still no joy. > > > > > > Trying to compile the program yields "error: `NAN' undeclared (first use > > > in this function)". > > > > > > Can anyone point me in the right direction? > > > > #ifndef NAN > > #define NAN (0.0/0.0) > > #endif > > > > > > -- > > GDB has a 'break' feature; why doesn't it have 'fix' too? > > > > I'm told that math.h should do this for me. Moreover, I think NAN is a > machine dependent value. > > Adding the line you mention would break on VAX (assuming I understand > this correctly). Although I don't think anyone would run this program > on a VAX, if it's in the ports tree there's the possibility. > > Worst case, I could add those defines though. > > Thanks. > Jim
Is your source familiar with OpenBSD? You say C99 math.h supposedly provides NAN. math(3) says nothing about C99. That's your first clue. Looking through gcc(1) for -std=c99 points to the GCC webpage [1]. It says "additional math library functions" are missing. That might be another clue. If you can't use NAN in a simple test program using -std=c99 and/or -lm, you're SOL unless you start patching your program. Both math(3) and the source for isnan(3) (see [2]) indicate that there are many potential NaN values. Unless you know exactly what this program is doing or are very familiar with your arch's floating point support, don't assume that #define will work 100% of the time. I'm no expert though. Good luck. --david [1] http://gcc.gnu.org/gcc-3.3/c99status.html [2] http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libm/src/s_isnan.c
