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.

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

   acosf(), acosl():
       _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
           || /* Since glibc 2.19: */ _DEFAULT_SOURCE
           || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION

   These  functions calculate the arc cosine of x; that is the value whose
   cosine is x.

RETURN VALUE

   On success, these functions return the arc cosine of x in radians;  the
   return value is in the range [0, pi].

   If x is a NaN, a NaN is returned.

   If x is +1, +0 is returned.

   If  x is positive infinity or negative infinity, a domain error occurs,
   and a NaN is returned.

   If x is outside the range [-1, 1], a domain error occurs, and a NaN  is
   returned.

ERRORS

   See  math_error(7) for information on how to determine whether an error
   has occurred when calling these functions.

   The following errors can occur:

   Domain error: x is outside the range [-1, 1]
          errno is set  to  EDOM.   An  invalid  floating-point  exception
          (FE_INVALID) is raised.

ATTRIBUTES

   For   an   explanation   of   the  terms  used  in  this  section,  see
   attributes(7).

   
   Interface                 Attribute      Value   
   
   acos(), acosf(), acosl()  Thread safety  MT-Safe 
   

CONFORMING TO

   C99, POSIX.1-2001, POSIX.1-2008.

   The variant returning double also conforms to SVr4, 4.3BSD, C89.

SEE ALSO

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

COLOPHON

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   https://www.kernel.org/doc/man-pages/.

                              2016-03-15                           ACOS(3)

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