1COS(3P)                    POSIX Programmer's Manual                   COS(3P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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11

NAME

13       cos, cosf, cosl — cosine function
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SYNOPSIS

16       #include <math.h>
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18       double cos(double x);
19       float cosf(float x);
20       long double cosl(long double x);
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DESCRIPTION

23       The functionality described on this reference page is aligned with  the
24       ISO C  standard.  Any  conflict between the requirements described here
25       and the ISO C standard is unintentional. This  volume  of  POSIX.1‐2008
26       defers to the ISO C standard.
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28       These  functions shall compute the cosine of their argument x, measured
29       in radians.
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31       An application wishing to check for error situations should  set  errno
32       to  zero  and  call  feclearexcept(FE_ALL_EXCEPT)  before calling these
33       functions. On return, if errno is non-zero or fetestexcept(FE_INVALID |
34       FE_DIVBYZERO  |  FE_OVERFLOW  | FE_UNDERFLOW) is non-zero, an error has
35       occurred.
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RETURN VALUE

38       Upon successful completion, these functions shall return the cosine  of
39       x.
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41       If x is NaN, a NaN shall be returned.
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43       If x is ±0, the value 1.0 shall be returned.
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45       If x is ±Inf, a domain error shall occur, and a NaN shall be returned.
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ERRORS

48       These functions shall fail if:
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50       Domain Error
51                   The x argument is ±Inf.
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53                   If  the  integer expression (math_errhandling & MATH_ERRNO)
54                   is non-zero, then errno shall be set  to  [EDOM].   If  the
55                   integer  expression  (math_errhandling & MATH_ERREXCEPT) is
56                   non-zero, then the invalid floating-point  exception  shall
57                   be raised.
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59       The following sections are informative.
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EXAMPLES

62   Taking the Cosine of a 45-Degree Angle
63           #include <math.h>
64           ...
65           double radians = 45 * M_PI / 180;
66           double result;
67           ...
68           result = cos(radians);
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APPLICATION USAGE

71       These  functions  may  lose accuracy when their argument is near an odd
72       multiple of π/2 or is far from 0.
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74       On  error,  the  expressions  (math_errhandling   &   MATH_ERRNO)   and
75       (math_errhandling  & MATH_ERREXCEPT) are independent of each other, but
76       at least one of them must be non-zero.
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RATIONALE

79       None.
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FUTURE DIRECTIONS

82       None.
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SEE ALSO

85       acos(), feclearexcept(), fetestexcept(), isnan(), sin(), tan()
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87       The Base Definitions volume of POSIX.1‐2008, Section 4.19, Treatment of
88       Error Conditions for Mathematical Functions, <math.h>
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91       Portions  of  this text are reprinted and reproduced in electronic form
92       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
93       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
94       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
95       cal  and  Electronics  Engineers,  Inc  and  The  Open Group.  (This is
96       POSIX.1-2008 with the 2013 Technical Corrigendum  1  applied.)  In  the
97       event of any discrepancy between this version and the original IEEE and
98       The Open Group Standard, the original IEEE and The Open Group  Standard
99       is  the  referee document. The original Standard can be obtained online
100       at http://www.unix.org/online.html .
101
102       Any typographical or formatting errors that appear  in  this  page  are
103       most likely to have been introduced during the conversion of the source
104       files to man page format. To report such errors,  see  https://www.ker‐
105       nel.org/doc/man-pages/reporting_bugs.html .
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109IEEE/The Open Group                  2013                              COS(3P)
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