# finite

## NAME



           finite, finitef, finitel, isinf, isinff, isinfl, isnan, isnanf,
           isnanl - BSD floating-point classification functions
    


## LIBRARY



           Math library (_libm_ , _-lm_)
    


## SYNOPSIS



           **#include <math.h>**
    
           **int finite(double** _x_**);**
           **int finitef(float** _x_**);**
           **int finitel(long double** _x_**);**
    
           **int isinf(double** _x_**);**
           **int isinff(float** _x_**);**
           **int isinfl(long double** _x_**);**
    
           **int isnan(double** _x_**);**
           **int isnanf(float** _x_**);**
           **int isnanl(long double** _x_**);**
    
       Feature Test Macro Requirements for glibc (see
       feature_test_macros(7)):
    
           **finite**(), **finitef**(), **finitel**():
               /* glibc >= 2.19: */ _DEFAULT_SOURCE
                   || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
    
           **isinf**():
               _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE
                   || /* glibc >= 2.19: */ _DEFAULT_SOURCE
                   || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
    
           **isinff**(), **isinfl**():
               /* glibc >= 2.19: */ _DEFAULT_SOURCE
                   || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
    
           **isnan**():
               _XOPEN_SOURCE || _ISOC99_SOURCE
                   || /* glibc >= 2.19: */ _DEFAULT_SOURCE
                   || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
    
           **isnanf**(), **isnanl**():
               _XOPEN_SOURCE >= 600
                   || /* glibc >= 2.19: */ _DEFAULT_SOURCE
                   || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
    


## DESCRIPTION



           The **finite**(), **finitef**(), and **finitel**() functions return a nonzero
           value if _x_ is neither infinite nor a "not-a-number" (NaN) value,
           and 0 otherwise.
    
           The **isnan**(), **isnanf**(), and **isnanl**() functions return a nonzero
           value if _x_ is a NaN value, and 0 otherwise.
    
           The **isinf**(), **isinff**(), and **isinfl**() functions return 1 if _x_ is
           positive infinity, -1 if _x_ is negative infinity, and 0 otherwise.
    


## ATTRIBUTES



           For an explanation of the terms used in this section, see
           attributes(7).
           ┌──────────────────────────────────────┬───────────────┬─────────┐
           │ **Interface** │ **Attribute** │ **Value** │
           ├──────────────────────────────────────┼───────────────┼─────────┤
           │ **finite**(), **finitef**(), **finitel**(),      │ Thread safety │ MT-Safe │
           │ **isinf**(), **isinff**(), **isinfl**(),         │               │         │
           │ **isnan**(), **isnanf**(), **isnanl**()          │               │         │
           └──────────────────────────────────────┴───────────────┴─────────┘
    


## NOTES



           Note that these functions are obsolete.  C99 defines macros
           **isfinite**(), **isinf**(), and **isnan**() (for all types) replacing them.
           Further note that the C99 **isinf**() has weaker guarantees on the
           return value.  See fpclassify(3).
    


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