Calculate the principal value of the arc cosine of the input argument x.
- Returns:
- Result will be in the interval [0,
] for x inside [-1, +1].
- acosf(1) returns +0.
- acosf(
x) returns NaN for x outside [-1, +1].
- Note:
- For accuracy information for this function see the CUDA C Programming Guide, Appendix C, Table C-1.