функции обратного гиперболического тангенса (inverse hyperbolic tangent functions)
Пролог (Prolog)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
Имя (Name)
atanh, atanhf, atanhl — inverse hyperbolic tangent functions
Синопсис (Synopsis)
#include <math.h>
double atanh(double x);
float atanhf(float x);
long double atanhl(long double x);
Описание (Description)
The functionality described on this reference page is aligned
with the ISO C standard. Any conflict between the requirements
described here and the ISO C standard is unintentional. This
volume of POSIX.1‐2017 defers to the ISO C standard.
These functions shall compute the inverse hyperbolic tangent of
their argument x.
An application wishing to check for error situations should set
errno to zero and call feclearexcept(FE_ALL_EXCEPT) before
calling these functions. On return, if errno is non-zero or
fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW |
FE_UNDERFLOW) is non-zero, an error has occurred.
Возвращаемое значение (Return value)
Upon successful completion, these functions shall return the
inverse hyperbolic tangent of their argument.
If x is ±1, a pole error shall occur, and atanh(), atanhf(), and
atanhl() shall return the value of the macro HUGE_VAL, HUGE_VALF,
and HUGE_VALL, respectively, with the same sign as the correct
value of the function.
For finite |x|>1, a domain error shall occur, and either a NaN
(if supported), or an implementation-defined value shall be
returned.
If x is NaN, a NaN shall be returned.
If x is ±0, x shall be returned.
If x is ±Inf, a domain error shall occur, and a NaN shall be
returned.
If x is subnormal, a range error may occur
and x should be returned.
If x is not returned, atanh(), atanhf(), and atanhl() shall
return an implementation-defined value no greater in magnitude
than DBL_MIN, FLT_MIN, and LDBL_MIN, respectively.
Ошибки (Error)
These functions shall fail if:
Domain Error
The x argument is finite and not in the range [-1,1],
or is ±Inf.
If the integer expression (math_errhandling &
MATH_ERRNO) is non-zero, then errno shall be set to
[EDOM]. If the integer expression (math_errhandling
& MATH_ERREXCEPT) is non-zero, then the invalid
floating-point exception shall be raised.
Pole Error The x argument is ±1.
If the integer expression (math_errhandling &
MATH_ERRNO) is non-zero, then errno shall be set to
[ERANGE]. If the integer expression
(math_errhandling & MATH_ERREXCEPT) is non-zero, then
the divide-by-zero floating-point exception shall be
raised.
These functions may fail if:
Range Error The value of x is subnormal.
If the integer expression (math_errhandling &
MATH_ERRNO) is non-zero, then errno shall be set to
[ERANGE]. If the integer expression
(math_errhandling & MATH_ERREXCEPT) is non-zero, then
the underflow floating-point exception shall be
raised.
The following sections are informative.
Примеры (Examples)
None.
Использование в приложениях (Application usage)
On error, the expressions (math_errhandling & MATH_ERRNO) and
(math_errhandling & MATH_ERREXCEPT) are independent of each
other, but at least one of them must be non-zero.
Обоснование (Rationale)
None.
Будущие направления (Future directions)
None.
Смотри также (See also)
feclearexcept(3p), fetestexcept(3p), tanh(3p)
The Base Definitions volume of POSIX.1‐2017, Section 4.20,
Treatment of Error Conditions for Mathematical Functions,
math.h(0p)
