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

6       nearbyint,  nearbyintf, nearbyintl, rint, rintf, rintl - round to near‐
7       est integer
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SYNOPSIS

10       #include <math.h>
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12       double nearbyint(double x);
13       float nearbyintf(float x);
14       long double nearbyintl(long double x);
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16       double rint(double x);
17       float rintf(float x);
18       long double rintl(long double x);
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20       Link with -lm.
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22   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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24       nearbyint(), nearbyintf(), nearbyintl():
25           _XOPEN_SOURCE >= 600 || _POSIX_C_SOURCE >= 200112L ||
26           _ISOC99_SOURCE;
27           or cc -std=c99
28       rint():
29           _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 ||
30           _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED || _ISOC99_SOURCE ||
31           _POSIX_C_SOURCE >= 200112L;
32           or cc -std=c99
33       rintf(), rintl():
34           _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 ||
35           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
36           or cc -std=c99
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DESCRIPTION

39       The nearbyint() functions round their argument to an integer  value  in
40       floating-point  format,  using the current rounding direction (see fes‐
41       etround(3)) and without raising the inexact exception.
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43       The rint() functions do the same, but will raise the inexact  exception
44       (FE_INEXACT,  checkable via fetestexcept(3)) when the result differs in
45       value from the argument.
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RETURN VALUE

48       These functions return the rounded integer value.
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50       If x is integral, +0, -0, NaN, or infinite, x itself is returned.
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ERRORS

53       No errors occur.  POSIX.1-2001 documents a range error  for  overflows,
54       but see NOTES.
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CONFORMING TO

57       C99, POSIX.1-2001.
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NOTES

60       SUSv2  and  POSIX.1-2001  contain  text about overflow (which might set
61       errno to ERANGE, or raise an FE_OVERFLOW exception).  In practice,  the
62       result  cannot  overflow on any current machine, so this error-handling
63       stuff is just nonsense.  (More precisely, overflow can happen only when
64       the  maximum  value  of the exponent is smaller than the number of man‐
65       tissa bits.  For the IEEE-754 standard 32-bit and 64-bit floating-point
66       numbers  the maximum value of the exponent is 128 (respectively, 1024),
67       and the number of mantissa bits is 24 (respectively, 53).)
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69       If you want to store the rounded value in an integer type, you probably
70       want to use one of the functions described in lrint(3) instead.
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SEE ALSO

73       ceil(3), floor(3), lrint(3), round(3), trunc(3)
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COLOPHON

76       This  page  is  part of release 3.53 of the Linux man-pages project.  A
77       description of the project, and information about reporting  bugs,  can
78       be found at http://www.kernel.org/doc/man-pages/.
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82                                  2010-09-20                           RINT(3)
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