MATH_ERRNO, MATH_ERREXCEPT, math_errhandling

 

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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/Comparison
fpclassify (C++11) isfinite (C++11) isinf (C++11) isnan (C++11) isnormal (C++11) signbit (C++11)	isgreater (C++11) isgreaterequal (C++11) isless (C++11) islessequal (C++11) islessgreater (C++11) isunordered (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)

 

Defined in header <cmath>
#define MATH_ERRNO        1		(since C++11)
#define MATH_ERREXCEPT    2		(since C++11)
#define math_errhandling  /*implementation defined*/		(since C++11)

The macro constant math_errhandling expands to an expression of type int that is either equal to MATH_ERRNO, or equal to MATH_ERREXCEPT, or equal to their bitwise OR (MATH_ERRNO | MATH_ERREXCEPT).

The value of math_errhandling indicates the type of error handling that is performed by the floating-point operators and functions:

Constant	Explanation
MATH_ERREXCEPT	indicates that floating-point exceptions are used: at least FE_DIVBYZERO, FE_INVALID, and FE_OVERFLOW are defined in <cfenv>.
MATH_ERRNO	indicates that floating-point operations use the variable errno to report errors.

The following floating-point error conditions are recognized:

1. Domain error (input argument is outside the range in which the operation is mathematically defined, e.g. std::sqrt(-1), std::log(-1), or std::acos(2)). If MATH_ERRNO bit is set, EDOM is assigned to errno. If MATH_ERREXCEPT bit is set, FE_INVALID is raised.
2. Range error (the mathematical result cannot be represented as the object of specified type, e.g. std::atanh(-1), std::log(0.0), or std::lgamma(0.0)). If MATH_ERRNO bit is set, ERANGE is assigned to errno. If MATH_ERREXCEPT bit is set, FE_DIVBYZERO or FE_OVERFLOW is raised.
3. Overflow (the mathematical result is finite, but too big to be represented without extreme roundoff error, e.g. functions such as std::exp with sufficiently large arguments). If MATH_ERRNO bit is set, ERANGE is assigned to errno. If MATH_ERREXCEPT bit is set, FE_OVERFLOW is raised.
4. Underflow (the mathematical result is non-zero, but too small to be represented without extreme roundoff error, e.g. the result is subnormal, as in std::sin(subnormal) or for many other functions with subnormal arguments). If MATH_ERRNO bit is set, ERANGE may be assigned to errno. If MATH_ERREXCEPT bit is set, FE_UNDERFLOW may be raised.

See also

FE_ALL_EXCEPT FE_DIVBYZERO FE_INEXACT FE_INVALID FE_OVERFLOW FE_UNDERFLOW (C++11)	floating-point exceptions (macro constant)
errno	macro which expands to POSIX-compatible thread-local error number variable (macro variable)