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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 these macros.  The macros
       are guaranteed to evaluate their operands only once.  The operands  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 argument 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 3.35 of the Linux man-pages project.  A  description  of  the
       project,  and information about reporting bugs, can be found at http://man7.org/linux/man-
       pages/.

                                            2010-09-20                               ISGREATER(3)