1RINT(3) Linux Programmer's Manual RINT(3)
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6 nearbyint, nearbyintf, nearbyintl, rint, rintf, rintl - round to near‐
7 est integer
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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 _POSIX_C_SOURCE >= 200112L || _ISOC99_SOURCE
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27 rint():
28 _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
29 || _XOPEN_SOURCE >= 500
30 || /* Since glibc 2.19: */ _DEFAULT_SOURCE
31 || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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33 rintf(), rintl():
34 _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
35 || /* Since glibc 2.19: */ _DEFAULT_SOURCE
36 || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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39 The nearbyint(), nearbyintf(), and nearbyintl() functions round their
40 argument to an integer value in floating-point format, using the cur‐
41 rent rounding direction (see fesetround(3)) and without raising the in‐
42 exact exception. When the current rounding direction is to nearest,
43 these functions round halfway cases to the even integer in accordance
44 with IEEE-754.
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46 The rint(), rintf(), and rintl() functions do the same, but will raise
47 the inexact exception (FE_INEXACT, checkable via fetestexcept(3)) when
48 the result differs in value from the argument.
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51 These functions return the rounded integer value.
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53 If x is integral, +0, -0, NaN, or infinite, x itself is returned.
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56 No errors occur. POSIX.1-2001 documents a range error for overflows,
57 but see NOTES.
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60 For an explanation of the terms used in this section, see at‐
61 tributes(7).
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63 ┌────────────────────────────────────────────┬───────────────┬─────────┐
64 │Interface │ Attribute │ Value │
65 ├────────────────────────────────────────────┼───────────────┼─────────┤
66 │nearbyint(), nearbyintf(), nearbyintl(), │ Thread safety │ MT-Safe │
67 │rint(), rintf(), rintl() │ │ │
68 └────────────────────────────────────────────┴───────────────┴─────────┘
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71 C99, POSIX.1-2001, POSIX.1-2008.
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74 SUSv2 and POSIX.1-2001 contain text about overflow (which might set er‐
75 rno to ERANGE, or raise an FE_OVERFLOW exception). In practice, the
76 result cannot overflow on any current machine, so this error-handling
77 stuff is just nonsense. (More precisely, overflow can happen only when
78 the maximum value of the exponent is smaller than the number of mantis‐
79 sa bits. For the IEEE-754 standard 32-bit and 64-bit floating-point
80 numbers the maximum value of the exponent is 128 (respectively, 1024),
81 and the number of mantissa bits is 24 (respectively, 53).)
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83 If you want to store the rounded value in an integer type, you probably
84 want to use one of the functions described in lrint(3) instead.
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87 ceil(3), floor(3), lrint(3), round(3), trunc(3)
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90 This page is part of release 5.13 of the Linux man-pages project. A
91 description of the project, information about reporting bugs, and the
92 latest version of this page, can be found at
93 https://www.kernel.org/doc/man-pages/.
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97 2021-03-22 RINT(3)