ISGREATER(3)                                        Linux Programmer's Manual                                       ISGREATER(3)



NAME
       isgreater,  isgreaterequal,  isless,  islessequal,  islessgreater,  isunordered - floating-point relational tests without
       exception for NaN

SYNOPSIS
       #include <math.h>

       int isgreater(x, y);

       int isgreaterequal(x, y);

       int isless(x, y);

       int islessequal(x, y);

       int islessgreater(x, y);

       int isunordered(x, y);

       Link with -lm.

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       All functions described here: _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE; or cc -std=c99

DESCRIPTION
       The normal relation operations (like <, "less than") will fail if one of the operands is NaN.  This will cause an  excep-
       tion.  To avoid this, C99 defines these macros.  The macros are guaranteed to evaluate their operands only once.  The op-
       erands can be of any real floating-point type.

       isgreater()
              determines (x) > (y) without an exception if x or y is NaN.

       isgreaterequal()
              determines (x) >= (y) without an exception if x or y is NaN.

       isless()
              determines (x) < (y) without an exception if x or y is NaN.

       islessequal()
              determines (x) <= (y) without an exception if x or y is NaN.

       islessgreater()
              determines (x) < (y) || (x) > (y) without an exception if x or y is NaN.  This macro is not equivalent  to  x != y
              because that expression is true if x or y is NaN.

       isunordered()
              determines whether its arguments are unordered, that is, whether at least one of the arguments is a NaN.

RETURN VALUE
       The macros other than isunordered() return the result of the relational comparison; these macros return 0 if either argu-
       ment is a NaN.

       isunordered() returns 1 if x or y is NaN and 0 otherwise.

ERRORS
       No errors occur.

CONFORMING TO
       C99, POSIX.1-2001.

NOTES
       Not all hardware supports these functions, and where hardware support isn't provided, they will be  emulated  by  macros.
       This will result in a performance penalty.  Don't use these functions if NaN is of no concern for you.

SEE ALSO
       fpclassify(3), isnan(3)

COLOPHON
       This  page  is  part of release 3.25 of the Linux man-pages project.  A description of the project, and information about
       reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



                                                           2008-08-05                                               ISGREATER(3)