c/numeric/math/acos

@1-6@ Computes the principal value of the arc cosine of. @7@ Type-generic macro: If the argument has type,  is called. Otherwise, if the argument has integer type or the type,  is called. Otherwise,  is called. If the argument is complex, then the macro invokes the corresponding complex function (cacosf, cacos, cacosl).

Return value
If no errors occur, the arc cosine of ($arccos(arg)$) in the range $[0 ; &pi;]$, is returned.

If a domain error occurs, an implementation-defined value is returned (NaN where supported).

If a range error occurs due to underflow, the correct result (after rounding) is returned.

Error handling
Errors are reported as specified in.

Domain error occurs if is outside the range.

If the implementation supports IEEE floating-point arithmetic (IEC 60559):
 * If the argument is $+1$, the value is returned;
 * If $|arg| > 1$, a domain error occurs and NaN is returned;
 * if the argument is NaN, NaN is returned.