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fea681da | 1 | .\" Copyright 2001 Andries Brouwer <aeb@cwi.nl>. |
2517f764 MK |
2 | .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk |
3 | .\" <mtk.manpages@gmail.com> | |
fea681da | 4 | .\" |
93015253 | 5 | .\" %%%LICENSE_START(VERBATIM) |
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6 | .\" Permission is granted to make and distribute verbatim copies of this |
7 | .\" manual provided the copyright notice and this permission notice are | |
8 | .\" preserved on all copies. | |
9 | .\" | |
10 | .\" Permission is granted to copy and distribute modified versions of this | |
11 | .\" manual under the conditions for verbatim copying, provided that the | |
12 | .\" entire resulting derived work is distributed under the terms of a | |
13 | .\" permission notice identical to this one. | |
c13182ef | 14 | .\" |
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15 | .\" Since the Linux kernel and libraries are constantly changing, this |
16 | .\" manual page may be incorrect or out-of-date. The author(s) assume no | |
17 | .\" responsibility for errors or omissions, or for damages resulting from | |
18 | .\" the use of the information contained herein. The author(s) may not | |
19 | .\" have taken the same level of care in the production of this manual, | |
20 | .\" which is licensed free of charge, as they might when working | |
21 | .\" professionally. | |
c13182ef | 22 | .\" |
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23 | .\" Formatted or processed versions of this manual, if unaccompanied by |
24 | .\" the source, must acknowledge the copyright and authors of this work. | |
4b72fb64 | 25 | .\" %%%LICENSE_END |
fea681da | 26 | .\" |
4b8c67d9 | 27 | .TH RINT 3 2017-09-15 "" "Linux Programmer's Manual" |
fea681da | 28 | .SH NAME |
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29 | nearbyint, nearbyintf, nearbyintl, rint, rintf, rintl \- round |
30 | to nearest integer | |
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31 | .SH SYNOPSIS |
32 | .nf | |
33 | .B #include <math.h> | |
68e4db0a | 34 | .PP |
fea681da | 35 | .BI "double nearbyint(double " x ); |
fea681da | 36 | .BI "float nearbyintf(float " x ); |
fea681da | 37 | .BI "long double nearbyintl(long double " x ); |
68e4db0a | 38 | .PP |
fea681da | 39 | .BI "double rint(double " x ); |
fea681da | 40 | .BI "float rintf(float " x ); |
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41 | .BI "long double rintl(long double " x ); |
42 | .fi | |
68e4db0a | 43 | .PP |
20c58d70 | 44 | Link with \fI\-lm\fP. |
68e4db0a | 45 | .PP |
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46 | .in -4n |
47 | Feature Test Macro Requirements for glibc (see | |
48 | .BR feature_test_macros (7)): | |
49 | .in | |
68e4db0a | 50 | .PP |
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51 | .ad l |
52 | .BR nearbyint (), | |
53 | .BR nearbyintf (), | |
54 | .BR nearbyintl (): | |
27311437 | 55 | .RS 4 |
cd2d5ec1 | 56 | _POSIX_C_SOURCE\ >=\ 200112L || _ISOC99_SOURCE |
27311437 | 57 | .RE |
cc4615cc | 58 | .br |
2517f764 | 59 | .BR rint (): |
27311437 | 60 | .RS 4 |
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61 | _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L |
62 | || _XOPEN_SOURCE\ >=\ 500 | |
cf7fa0a1 | 63 | .\" || _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED |
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64 | || /* Since glibc 2.19: */ _DEFAULT_SOURCE |
65 | || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE | |
27311437 | 66 | .RE |
2517f764 | 67 | .br |
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68 | .BR rintf (), |
69 | .BR rintl (): | |
27311437 | 70 | .RS 4 |
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71 | _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L |
72 | || /* Since glibc 2.19: */ _DEFAULT_SOURCE | |
73 | || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE | |
27311437 | 74 | .RE |
cc4615cc | 75 | .ad b |
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76 | .SH DESCRIPTION |
77 | The | |
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78 | .BR nearbyint (), |
79 | .BR nearbyintf (), | |
80 | and | |
81 | .BR nearbyintl () | |
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82 | functions round their argument to an integer value in floating-point |
83 | format, using the current rounding direction (see | |
84 | .BR fesetround (3)) | |
85 | and without raising the | |
fea681da | 86 | .I inexact |
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87 | exception. |
88 | When the current rounding direction is to nearest, these | |
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89 | functions round halfway cases to the even integer in accordance with |
90 | IEEE-754. | |
dd3568a1 | 91 | .PP |
fea681da | 92 | The |
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93 | .BR rint (), |
94 | .BR rintf (), | |
95 | and | |
96 | .BR rintl () | |
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97 | functions do the same, but will raise the |
98 | .I inexact | |
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99 | exception |
100 | .RB ( FE_INEXACT , | |
101 | checkable via | |
102 | .BR fetestexcept (3)) | |
103 | when the result differs in value from the argument. | |
47297adb | 104 | .SH RETURN VALUE |
2517f764 | 105 | These functions return the rounded integer value. |
847e0d88 | 106 | .PP |
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107 | If |
108 | .I x | |
109 | is integral, +0, \-0, NaN, or infinite, | |
110 | .I x | |
111 | itself is returned. | |
fea681da | 112 | .SH ERRORS |
2517f764 | 113 | No errors occur. |
efe294cb | 114 | POSIX.1-2001 documents a range error for overflows, but see NOTES. |
36981c13 | 115 | .SH ATTRIBUTES |
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116 | For an explanation of the terms used in this section, see |
117 | .BR attributes (7). | |
118 | .TS | |
119 | allbox; | |
120 | lbw26 lb lb | |
121 | l l l. | |
122 | Interface Attribute Value | |
123 | T{ | |
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124 | .BR nearbyint (), |
125 | .BR nearbyintf (), | |
dd47b706 | 126 | .br |
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127 | .BR nearbyintl (), |
128 | .BR rint (), | |
dd47b706 | 129 | .br |
36981c13 | 130 | .BR rintf (), |
36981c13 | 131 | .BR rintl () |
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132 | T} Thread safety MT-Safe |
133 | .TE | |
47297adb | 134 | .SH CONFORMING TO |
9a74e018 | 135 | C99, POSIX.1-2001, POSIX.1-2008. |
fea681da | 136 | .SH NOTES |
68e1685c | 137 | SUSv2 and POSIX.1-2001 contain text about overflow (which might set |
fea681da | 138 | .I errno |
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139 | to |
140 | .BR ERANGE , | |
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141 | or raise an |
142 | .B FE_OVERFLOW | |
143 | exception). | |
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144 | In practice, the result cannot overflow on any current machine, |
145 | so this error-handling stuff is just nonsense. | |
146 | (More precisely, overflow can happen only when the maximum value | |
147 | of the exponent is smaller than the number of mantissa bits. | |
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148 | For the IEEE-754 standard 32-bit and 64-bit floating-point numbers |
149 | the maximum value of the exponent is 128 (respectively, 1024), | |
150 | and the number of mantissa bits is 24 (respectively, 53).) | |
847e0d88 | 151 | .PP |
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152 | If you want to store the rounded value in an integer type, |
153 | you probably want to use one of the functions described in | |
154 | .BR lrint (3) | |
155 | instead. | |
47297adb | 156 | .SH SEE ALSO |
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157 | .BR ceil (3), |
158 | .BR floor (3), | |
159 | .BR lrint (3), | |
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160 | .BR round (3), |
161 | .BR trunc (3) |