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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 ||
              _POSIX_C_SOURCE >= 200112L;
              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 exception.  To avoid  this,
       C99 defines the macros listed below.

       These macros are guaranteed to evaluate their arguments only once.  The
       arguments must be of  real  floating-point  type  (note:  do  not  pass
       integer  values  as arguments to these macros, since the arguments will
       not be promoted to real-floating types).

       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 argument is a NaN.

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

ERRORS

       No errors occur.

ATTRIBUTES

   Multithreading (see pthreads(7))
       The    isgreater(),    isgreaterequal(),    isless(),    islessequal(),
       islessgreater(), and isunordered() macros are thread-safe.

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 3.65 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/.

                                  2014-01-27                      ISGREATER(3)



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