Open System Services Library Calls Reference Manual (G06.27+, H06.04+)

OSS Library Calls (a - d) atanh(3)
STANDARDS CONFORMANCE
The XPG4 Version 2 specification leaves some features to the implementing vendor to define.
The following features are affected in the HP implementation:
• When used for IEEE floating-point values, this function does not set errno to [EDOM]
when the value of x is NaN.
• When used for Tandem floating-point values, this function does not return the value NaN
when an invalid parameter is passed.
527187-004 Hewlett-Packard Company 1−21