acosf(3) -- Linux man page

 

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);
 

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

SVID 3, POSIX, BSD 4.3, ISO 9899. The float and long double variants are C99 requirements.  

SEE ALSO

asin(3), atan(3), atan2(3), cos(3), sin(3), tan(3)