Open System Services Library Calls Reference Manual (G06.28+, H06.05+)

OSS Library Calls (a - d) acos(3)
STANDARDS CONFORMANCE
This function conforms to the XPG4 Version 2 specification with extensions when used for IEEE
floating-point format data. This function conforms to the XPG4 Version 2 specification without
extensions when used for Tandem floating-point data.
The XPG4 Version 2 specification leaves some features to the implementing vendor to define.
The following feature is affected in the HP implementation:
• For IEEE floating-point values, errno is not set to [EDOM] when the
value of x is NaN.
527187-007 Hewlett-Packard Company 1−9