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

  .