1ROUND(3P)                  POSIX Programmer's Manual                 ROUND(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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NAME

12       round, roundf, roundl - round to the nearest integer value in a  float‐
13       ing-point format
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SYNOPSIS

16       #include <math.h>
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18       double round(double x);
19       float roundf(float x);
20       long double roundl(long double x);
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DESCRIPTION

24       These functions shall round their argument to the nearest integer value
25       in floating-point  format,  rounding  halfway  cases  away  from  zero,
26       regardless of the current rounding direction.
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28       An  application  wishing to check for error situations should set errno
29       to zero and  call  feclearexcept(FE_ALL_EXCEPT)  before  calling  these
30       functions.   On return, if errno is non-zero or fetestexcept(FE_INVALID
31       | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error  has
32       occurred.
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RETURN VALUE

35       Upon  successful  completion,  these functions shall return the rounded
36       integer value.
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38       If x is NaN, a NaN shall be returned.
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40       If x is ±0 or ±Inf, x shall be returned.
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42       If the correct value would cause overflow, a range  error  shall  occur
43       and round(), roundf(), and roundl() shall return the value of the macro
44       ±HUGE_VAL, ±HUGE_VALF, and  ±HUGE_VALL  (with  the  same  sign  as  x),
45       respectively.
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ERRORS

48       These functions may fail if:
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50       Range Error
51              The result overflows.
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53       If  the integer expression (math_errhandling & MATH_ERRNO) is non-zero,
54       then errno  shall  be  set  to  [ERANGE].  If  the  integer  expression
55       (math_errhandling  &  MATH_ERREXCEPT)  is  non-zero,  then the overflow
56       floating-point exception shall be raised.
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59       The following sections are informative.
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EXAMPLES

62       None.
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APPLICATION USAGE

65       On  error,  the  expressions  (math_errhandling   &   MATH_ERRNO)   and
66       (math_errhandling  & MATH_ERREXCEPT) are independent of each other, but
67       at least one of them must be non-zero.
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RATIONALE

70       None.
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FUTURE DIRECTIONS

73       None.
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SEE ALSO

76       feclearexcept(),  fetestexcept(),  the  Base  Definitions   volume   of
77       IEEE Std 1003.1-2001,  Section  4.18, Treatment of Error Conditions for
78       Mathematical Functions, <math.h>
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81       Portions of this text are reprinted and reproduced in  electronic  form
82       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
83       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
84       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
85       Electrical and Electronics Engineers, Inc and The Open  Group.  In  the
86       event of any discrepancy between this version and the original IEEE and
87       The Open Group Standard, the original IEEE and The Open Group  Standard
88       is  the  referee document. The original Standard can be obtained online
89       at http://www.opengroup.org/unix/online.html .
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93IEEE/The Open Group                  2003                            ROUND(3P)
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