1RINT(3P)                   POSIX Programmer's Manual                  RINT(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       rint, rintf, rintl - round-to-nearest integral value
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SYNOPSIS

15       #include <math.h>
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17       double rint(double x);
18       float rintf(float x);
19       long double rintl(long double x);
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21

DESCRIPTION

23       These functions shall return the integral value (represented as a  dou‐
24       ble)  nearest x in the direction of the current rounding mode. The cur‐
25       rent rounding mode is implementation-defined.
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27       If the current rounding mode  rounds  toward  negative  infinity,  then
28       rint()  shall  be  equivalent  to floor(). If the current rounding mode
29       rounds toward positive infinity, then rint()  shall  be  equivalent  to
30       ceil().
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32       These  functions differ from the nearbyint(), nearbyintf(), and nearby‐
33       intl() functions only in that they may raise the inexact floating-point
34       exception if the result differs in value from the argument.
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36       An  application  wishing to check for error situations should set errno
37       to zero and  call  feclearexcept(FE_ALL_EXCEPT)  before  calling  these
38       functions.   On return, if errno is non-zero or fetestexcept(FE_INVALID
39       | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error  has
40       occurred.
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RETURN VALUE

43       Upon  successful  completion,  these functions shall return the integer
44       (represented as a double precision number) nearest x in  the  direction
45       of the current rounding mode.
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47       If x is NaN, a NaN shall be returned.
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49       If x is ±0 or ±Inf, x shall be returned.
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51       If  the  correct  value would cause overflow, a range error shall occur
52       and rint(), rintf(), and rintl() shall return the value  of  the  macro
53       ±HUGE_VAL,  ±HUGE_VALF,  and  ±HUGE_VALL  (with  the  same  sign as x),
54       respectively.
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ERRORS

57       These functions shall fail if:
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59       Range Error
60              The result would cause an overflow.
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62       If the integer expression (math_errhandling & MATH_ERRNO) is  non-zero,
63       then  errno  shall  be  set  to  [ERANGE].  If  the  integer expression
64       (math_errhandling & MATH_ERREXCEPT)  is  non-zero,  then  the  overflow
65       floating-point exception shall be raised.
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68       The following sections are informative.
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EXAMPLES

71       None.
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APPLICATION USAGE

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       abs(), ceil(), feclearexcept(), fetestexcept(), floor(), isnan(), near‐
86       byint(), the Base Definitions volume of  IEEE Std 1003.1-2001,  Section
87       4.18,   Treatment  of  Error  Conditions  for  Mathematical  Functions,
88       <math.h>
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91       Portions of this text are reprinted and reproduced in  electronic  form
92       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
93       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
94       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
95       Electrical and Electronics Engineers, Inc and The Open  Group.  In  the
96       event of any discrepancy between this version and the original IEEE and
97       The Open Group Standard, the original IEEE and The Open Group  Standard
98       is  the  referee document. The original Standard can be obtained online
99       at http://www.opengroup.org/unix/online.html .
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103IEEE/The Open Group                  2003                             RINT(3P)
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