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

NAME
 acos - arc cosine function
SYNOPSIS
 #include <math.h>
 double acos(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

SEE ALSO

asin, atan, atan2, cos, sin, tan,

 June 8, 1993 1

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