freebsd man page for atanh

ATANH(3)						   BSD Library Functions Manual 						  ATANH(3)

NAME
     atanh, atanhf, atanhl -- inverse hyperbolic tangent functions

LIBRARY
     Math Library (libm, -lm)

SYNOPSIS
     #include <math.h>

     double
     atanh(double x);

     float
     atanhf(float x);

     long double
     atanhl(long double x);

DESCRIPTION
     The atanh(), atanhf(), and atanhl() functions compute the inverse hyperbolic tangent of the real argument x.  For a discussion of error due
     to roundoff, see math(3).

RETURN VALUES
     These functions return the inverse hyperbolic tangent of x if successful.	If the argument has absolute value 1, a divide-by-zero exception
     is raised and an infinity is returned.  If |x| > 1, an invalid exception is raised and an NaN is returned.

SEE ALSO
     acosh(3), asinh(3), exp(3), fenv(3), math(3)

HISTORY
     The atanh(), atanhf(), and atanhl() functions appeared in 4.3BSD, FreeBSD 2.0, and FreeBSD 10.0, respectively.

BSD
								   June 9, 2013 							       BSD