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

OSS Library Calls (t - v) tan(3)
The XPG4 Version 2 specification leaves some features to the implementing vendor to define.
The following features are affected in the HP implementation:
• For IEEE floating-point data, errno is not set to [EDOM] when the value of x is NaN.
• errno is not set to [ERANGE] when underflow occurs.
• The tan() function cannot cause overflow so HUGE_VAL is not returned and errno is
not set to [ERANGE].
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