Synopsis
#include <math.h>
float atanhf(float val)
Description

atanhf returns the inverse hyperbolic tangent of val.

Fast math library behavior

If |x| ≥ 1, errno is set to EDOM and atanhf returns HUGE_VALF.

IEC 60559 math library behavior

If |val| > 1 atanhf returns NaN with signal.
If val is NaN, atanhf returns that NaN with no signal.
If val is 1, atanhf returns ∞ with signal.
If val is -1, atanhf returns -∞ with signal.

Portability

atanhf conforms to ISO/IEC 9899:1999 (C99).