Guardian Native C Library Calls Reference Manual (G06.29+, H06.08+, J06.03+)

Guardian Native C Library Calls (t - z) 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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