std::nan, std::nanf, std::nanl

 

C++

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Common mathematical functions

Functions
Basic operations
abs(int) labs llabs imaxabs (C++11) abs(float) fabs div ldiv lldiv imaxdiv (C++11) fmod	remainder (C++11) remquo (C++11) fma (C++11) fmax (C++11) fmin (C++11) fdim (C++11) nan nanf nanl (C++11) (C++11) (C++11)
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exp exp2 (C++11) expm1 (C++11)	log log10 log1p (C++11) log2 (C++11)
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sqrt cbrt (C++11)	hypot (C++11) pow
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sin cos tan asin acos atan atan2	sinh cosh tanh asinh (C++11) acosh (C++11) atanh (C++11)
Error and gamma functions
erf (C++11) erfc (C++11)	lgamma (C++11) tgamma (C++11)
Nearest integer floating point operations
ceil floor round lround llround (C++11) (C++11) (C++11)	trunc (C++11) nearbyint (C++11) rint lrint llrint (C++11) (C++11) (C++11)
Floating point manipulation functions
ldexp scalbn scalbln (C++11) (C++11) ilogb (C++11) logb (C++11)	frexp modf nextafter nexttoward (C++11) (C++11) copysign (C++11)
Classification
fpclassify (C++11) isfinite (C++11) isinf (C++11)	isnan (C++11) isnormal (C++11) signbit (C++11)
Macro constants
HUGE_VALF HUGE_VAL HUGE_VALL (C++11) (C++11) INFINITY (C++11) NAN (C++11) math_errhandling MATH_ERRNO MATH_ERREXCEPT (C++11)	FP_NORMAL FP_SUBNORMAL FP_ZERO FP_INFINITE FP_NAN (C++11) (C++11) (C++11) (C++11) (C++11) FLT_EVAL_METHOD (C++11)

 

Defined in header <cmath>
float nanf( const char* arg );		(since C++11)
double nan( const char* arg );		(since C++11)
long double nanl( const char* arg );		(since C++11)

Converts the implementation-defined character string arg into the corresponding quiet NaN value. The call std::nan("string") is equivalent to the call std::strtod("NAN(string)", (char**)NULL);.

Parameters

arg

-

narrow character string identifying the contents of a NaN, or an empty string

Return value

The NaN value that corresponds to the identifying string arg or zero if the implemntation does not support quiet NaNs.

See also

isnan (C++11)	checks if the given number is NaN (function)
quiet_NaN [static]	returns a quiet NaN value of the given floating-point type (public static member function of std::numeric_limits)