|ACOS(3)||Linux Programmer's Manual||ACOS(3)|
NAME¶acos, acosf, acosl - arc cosine function
double acos(double x); float acosf(float x); long double acosl(long double x);
Link with -lm.
DESCRIPTION¶These functions calculate the arc cosine of x; that is the value whose cosine is x.
RETURN VALUE¶On success, these functions return the arc cosine of x in radians; the return value is in the range [0, pi].
If x is a NaN, a NaN is returned.
If x is +1, +0 is returned.
If x is positive infinity or negative infinity, a domain error occurs, and a NaN is returned.
If x is outside the range [-1, 1], a domain error occurs, and a NaN is returned.
ERRORS¶See math_error(7) for information on how to determine whether an error has occurred when calling these functions.
The following errors can occur:
- Domain error: x is outside the range [-1, 1]
- errno is set to EDOM. An invalid floating-point exception (FE_INVALID) is raised.
ATTRIBUTES¶For an explanation of the terms used in this section, see attributes(7).
|acos (), acosf (), acosl ()||Thread safety||MT-Safe|
CONFORMING TO¶C99, POSIX.1-2001, POSIX.1-2008.
The variant returning double also conforms to SVr4, 4.3BSD, C89.
SEE ALSO¶asin(3), atan(3), atan2(3), cacos(3), cos(3), sin(3), tan(3)
COLOPHON¶This page is part of release 5.10 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.