The
acos ();
and the
acosf ();
functions compute the principal value of the arc cosine of
Fa x .
A domain error occurs for arguments not in the range
Bq -1 , +1 .
For a discussion of error due to roundoff, see
math(3).
RETURN VALUES
The
acos ();
and the
acosf ();
functions return the arc cosine in the range
Bq 0 ,
radians.
If:
| x | > 1
acos (x);
raises an invalid exception and returns an .
