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
26 rint():
27 _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
28 || _XOPEN_SOURCE >= 500
29 || /* Since glibc 2.19: */ _DEFAULT_SOURCE
30 || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
31 rintf(), rintl():
32 _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
33 || /* Since glibc 2.19: */ _DEFAULT_SOURCE
34 || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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37 The nearbyint(), nearbyintf(), and nearbyintl() functions round their
38 argument to an integer value in floating-point format, using the cur‐
39 rent rounding direction (see fesetround(3)) and without raising the
40 inexact exception. When the current rounding direction is to nearest,
41 these functions round halfway cases to the even integer in accordance
42 with IEEE-754.
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44 The rint(), rintf(), and rintl() functions do the same, but will raise
45 the inexact exception (FE_INEXACT, checkable via fetestexcept(3)) when
46 the result differs in value from the argument.
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49 These functions return the rounded integer value.
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51 If x is integral, +0, -0, NaN, or infinite, x itself is returned.
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54 No errors occur. POSIX.1-2001 documents a range error for overflows,
55 but see NOTES.
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58 For an explanation of the terms used in this section, see
59 attributes(7).
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61 ┌───────────────────────────┬───────────────┬─────────┐
62 │Interface │ Attribute │ Value │
63 ├───────────────────────────┼───────────────┼─────────┤
64 │nearbyint(), nearbyintf(), │ Thread safety │ MT-Safe │
65 │nearbyintl(), rint(), │ │ │
66 │rintf(), rintl() │ │ │
67 └───────────────────────────┴───────────────┴─────────┘
69 C99, POSIX.1-2001, POSIX.1-2008.
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72 SUSv2 and POSIX.1-2001 contain text about overflow (which might set
73 errno to ERANGE, or raise an FE_OVERFLOW exception). In practice, the
74 result cannot overflow on any current machine, so this error-handling
75 stuff is just nonsense. (More precisely, overflow can happen only when
76 the maximum value of the exponent is smaller than the number of man‐
77 tissa bits. For the IEEE-754 standard 32-bit and 64-bit floating-point
78 numbers the maximum value of the exponent is 128 (respectively, 1024),
79 and the number of mantissa bits is 24 (respectively, 53).)
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81 If you want to store the rounded value in an integer type, you probably
82 want to use one of the functions described in lrint(3) instead.
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85 ceil(3), floor(3), lrint(3), round(3), trunc(3)
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88 This page is part of release 4.15 of the Linux man-pages project. A
89 description of the project, information about reporting bugs, and the
90 latest version of this page, can be found at
91 https://www.kernel.org/doc/man-pages/.
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95 2017-09-15 RINT(3)