ACOS(3) Linux Programmer s Manual ACOS(3)

NAME acos, acosf, acosl - arc cosine function

SYNOPSIS #include <math.h>

double acos(double x); float acosf(float x); long double acosl(long double x);

Link with -lm.

DESCRIPTION The acos() function calculates the arc cosine of x; that is the value whose cosine is x. If x falls outside the range -1 to 1, acos() fails and errno is set.

RETURN VALUE The acos() function returns the arc cosine in radians and the value is mathematically defined to be between 0 and PI (inclusive).

ERRORS EDOM x is out of range.

CONFORMING TO SVr4, POSIX.1-2001, 4.3BSD, C89. The float and long double variants are C99 requirements.

SEE ALSO asin(3), atan(3), atan2(3), cacos(3), cos(3), sin(3), tan(3)

2004-10-06 ACOS(3)