# isgreater

## NAME



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


## LIBRARY



           Math library (_libm_ , _-lm_)
    


## 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_**);**
    
       Feature Test Macro Requirements for glibc (see
       feature_test_macros(7)):
    
               All functions described here:
                   _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
    


## DESCRIPTION



           The normal relational operations (like **<** , "less than") 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



           For an explanation of the terms used in this section, see
           attributes(7).
           ┌──────────────────────────────────────┬───────────────┬─────────┐
           │ **Interface** │ **Attribute** │ **Value** │
           ├──────────────────────────────────────┼───────────────┼─────────┤
           │ **isgreater**(), **isgreaterequal**(),       │ Thread safety │ MT-Safe │
           │ **isless**(), **islessequal**(),             │               │         │
           │ **islessgreater**(), **isunordered**()       │               │         │
           └──────────────────────────────────────┴───────────────┴─────────┘
    


## VERSIONS



           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.
    


## STANDARDS



           C11, POSIX.1-2008.
    


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