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acos (3)
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, C99. The float and long double vari-
ants are C99 requirements.
SEE ALSO
asin(3), atan(3), atan2(3), cacos(3), cos(3), sin(3), tan(3)
2004-10-06 ACOS(3)
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