osx man page for isunordered

ISGREATER(3)						   BSD Library Functions Manual 					      ISGREATER(3)

NAME
     isgreater, isgreaterequal, isless, islessequal, islessgreater, isunordered -- compare two floating-point numbers

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <math.h>

     int
     isgreater(real-floating x, real-floating y);

     int
     isgreaterequal(real-floating x, real-floating y);

     int
     isless(real-floating x, real-floating y);

     int
     islessequal(real-floating x, real-floating y);

     int
     islessgreater(real-floating x, real-floating y);

     int
     isunordered(real-floating x, real-floating y);

DESCRIPTION
     Each of the macros isgreater(), isgreaterequal(), isless(), islessequal(), and islessgreater() takes arguments x and y and returns a non-zero
     value if and only if its nominal relation on x and y is true.  These macros always return zero if either argument is not a number (NaN), but
     unlike the corresponding C operators, they never raise a floating point exception.

     The isunordered() macro takes arguments x and y, returning non-zero if either x or y is NaN.  For any pair of floating-point values, one of
     the relationships (less, greater, equal, unordered) holds.

SEE ALSO
     fpclassify(3), math(3), signbit(3)

STANDARDS
     The isgreater(), isgreaterequal(), isless(), islessequal(), islessgreater(), and isunordered() macros conform to ISO/IEC 9899:1999
     (``ISO C99'').

BSD
								 December 1, 2008							       BSD