Tribblix: manual page: atanh.3m

ATANH(3M) Mathematical Library Functions ATANH(3M)

NAME

atanh, atanhf, atanhl - inverse hyperbolic tangent functions

SYNOPSIS

c99 [ flag... ] file... -lm [ library... ]
#include <math.h>

double atanh(double x);

float atanhf(float x);

long double atanhl(long double x);

DESCRIPTION

These functions compute the inverse hyperbolic tangent of their
argument x.

RETURN VALUES

Upon successful completion, these functions return the inverse
hyperbolic tangent of their argument.

If x is +-1, a pole error occurs and atanh(), atanhf(), and atanhl()
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 occurs and a NaN is returned.

If x is NaN, NaN is returned.

If x is +0, x is returned.

If x is +Inf, a domain error occurs and a NaN is returned.

For exceptional cases, matherr(3M) tabulates the values to be
returned by atanh() as specified by SVID3 and XPG3.

ERRORS

These functions will 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_ERREXCEPT) is non-zero, the invalid floating-
point exception is raised.

The atanh() function sets errno to EDOM if the
absolute value of x is greater than 1.0.

Pole Error
The x argument is +-1.

If the integer expression (math_errhandling &
MATH_ERREXCEPT) is non-zero, then the divide-by-zero
floating-point exception is raised.

The atanh() function sets errno to ERANGE if the
absolute value of x is equal to 1.0.

USAGE

An application wanting to check for exceptions should call
feclearexcept(FE_ALL_EXCEPT) before calling these functions. On
return, if fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW |
FE_UNDERFLOW) is non-zero, an exception has been raised. An
application should either examine the return value or check the
floating point exception flags to detect exceptions.

An application can also set errno to 0 before calling atanh(). On
return, if errno is non-zero, an error has occurred. The atanhf() and
atanhl() functions do not set errno.

ATTRIBUTES