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atanh(3)

NAME

     atanh, atanhf -- inverse hyperbolic tangent functions

LIBRARY

     Math Library (libm, -lm)

SYNOPSIS

     #include <math.h>

     double
     atanh(double x);

     float
     atanhf(float x);

DESCRIPTION

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

RETURN VALUES

     The atanh() and the atanhf() functions return the inverse hyperbolic tan-
     gent 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() function appeared in 4.3BSD.

FreeBSD 5.4		       January 14, 2005 		   FreeBSD 5.4

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