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 argu‐
ment x.
RETURN VALUES
Upon successful completion, these functions return the inverse hyper‐
bolic 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 abso‐
lute value of x is equal to 1.0.
USAGE
An application wanting to check for exceptions should call feclearex‐
cept(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
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Standard │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │MT-Safe │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOfeclearexcept(3M), fetestexcept(3M), math.h(3HEAD), matherr(3M),
tanh(3M), attributes(5), standards(5)SunOS 5.10 12 Jul 2006 atanh(3M)