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

NAME         top

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

SYNOPSIS         top

       #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:
              _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L

DESCRIPTION         top

       The normal relational 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).

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

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

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

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

              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.

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

RETURN VALUE         top

       The macros other than isunordered() return the result of the
       relational comparison; these macros return 0 if either argument is a

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

ERRORS         top

       No errors occur.

ATTRIBUTES         top

       For an explanation of the terms used in this section, see

       │Interface                      Attribute     Value   │
       │isgreater(), isgreaterequal(), │ Thread safety │ MT-Safe │
       │isless(), islessequal(),       │               │         │
       │islessgreater(), isunordered() │               │         │

CONFORMING TO         top

       POSIX.1-2001, POSIX.1-2008, C99.

NOTES         top

       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         top

       fpclassify(3), isnan(3)

COLOPHON         top

       This page is part of release 4.11 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

                                 2016-03-15                     ISGREATER(3)

Pages that refer to this page: fpclassify(3)math_error(7)