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 || _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 3.74 of the Linux man-pages project.  A description of the
       project, information about reporting bugs, and the latest version of  this  page,  can  be
       found at http://www.kernel.org/doc/man-pages/.



                                            2014-01-27                               ISGREATER(3)