acosf(3)

1ACOS(3)                    Linux Programmer's Manual                   ACOS(3)
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NAME

6       acos, acosf, acosl - arc cosine function
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SYNOPSIS

9       #include <math.h>
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11       double acos(double x);
12       float acosf(float x);
13       long double acosl(long double x);
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15       Link with -lm.
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17   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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19       acosf(), acosl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600
20       || _ISOC99_SOURCE; or cc -std=c99
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DESCRIPTION

23       The acos() function calculates the arc cosine of x; that is  the  value
24       whose cosine is x.
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RETURN VALUE

27       On  success, these functions return the arc cosine of x in radians; the
28       return value is in the range [0, pi].
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30       If x is a NaN, a NaN is returned.
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32       If x is +1, +0 is returned.
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34       If x is positive infinity or negative infinity, a domain error  occurs,
35       and a NaN is returned.
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37       If  x is outside the range [-1, 1], a domain error occurs, and a NaN is
38       returned.
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ERRORS

41       See math_error(7) for information on how to determine whether an  error
42       has occurred when calling these functions.
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44       The following errors can occur:
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46       Domain error: x is outside the range [-1, 1]
47              errno  is  set  to  EDOM.   An  invalid floating-point exception
48              (FE_INVALID) is raised.
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CONFORMING TO

51       C99, POSIX.1-2001.  The variant returning double also conforms to SVr4,
52       4.3BSD, C89.
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COLOPHON

58       This  page  is  part of release 3.22 of the Linux man-pages project.  A
59       description of the project, and information about reporting  bugs,  can
60       be found at http://www.kernel.org/doc/man-pages/.
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64                                  2008-08-05                           ACOS(3)