islessequal

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  inte-
       ger  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.

       attributes(7).

       +-------------------------------+---------------+---------+
       |Interface                      | Attribute     | Value   |
       +-------------------------------+---------------+---------+
       |isgreater(), isgreaterequal(), | Thread safety | MT-Safe |
       |isless(), islessequal(),       |               |         |
       |islessgreater(), isunordered() |               |         |
       +-------------------------------+---------------+---------+
CONFORMING TO
       POSIX.1-2001, POSIX.1-2008, C99.

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
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                                  2015-08-08                      ISGREATER(3)
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