atanh(3M) Mathematical Library Functions atanh(3M)
NAME
atanh, atanhf, atanhl - inverse hyperbolic tangent functions
SYNOPSIS
cc [ 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
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Interface Stability |Standard |
+-----------------------------+-----------------------------+
|MT-Level |MT-Safe |
+-----------------------------+-----------------------------+
SEE ALSO
feclearexcept(3M), fetestexcept(3M), math.h(3HEAD), matherr(3M), tanh(3M), attributes(5), standards(5)
SunOS 5.10 1 Sep 2002 atanh(3M)
