atanh

atanh

Compute the inverse hyperbolic tangent

Portability: C99

SYNOPSIS
DESCRIPTION
RETURN VALUE
DIAGNOSTICS
RELATED FUNCTIONS
SEE ALSO

SYNOPSIS

   #include <math.h>

   double atanh(double x);
   float atanhf(float x);
   long double atanhl(long double x);

DESCRIPTION

atanh computes the inverse hyperbolic sine of the argument x, expressed by the following relation:

[IMAGE]

The function name atanhf should be used for float arguments, and atanhl for long double arguments. Alternately, if the header file tgmath.h is included, atanh may be used with any numeric argument type.

RETURN VALUE

atanh returns the inverse hyperbolic tangent of the argument x, provided that this value is defined and expressible.

DIAGNOSTICS

An error message is written to the standard error file (stderr) by the runtime library if x is outside the valid domain. In this case, atanh returns plus or minus HUGE_VAL for HFP, or a NaN for BFP. In BFP, atanh(-1.0) evaluates to negative infinity, and atanh(+1.0) to positive infinity.

If an error occurs in atanh, the _matherr or _matherb routine is called. You can supply your own version of_matherr or _matherb to suppress the diagnostic message or modify the value returned.

RELATED FUNCTIONS

acosh, asinh, _matherb, _matherr

SEE ALSO

"Mathematical Functions" in Chapter 2, "Function Categories"

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