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fea681da | 1 | .\" Copyright 2001 Andries Brouwer <aeb@cwi.nl>. |
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2 | .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk |
3 | .\" <mtk.manpages@gmail.com> | |
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4 | .\" |
5 | .\" Permission is granted to make and distribute verbatim copies of this | |
6 | .\" manual provided the copyright notice and this permission notice are | |
7 | .\" preserved on all copies. | |
8 | .\" | |
9 | .\" Permission is granted to copy and distribute modified versions of this | |
10 | .\" manual under the conditions for verbatim copying, provided that the | |
11 | .\" entire resulting derived work is distributed under the terms of a | |
12 | .\" permission notice identical to this one. | |
c13182ef | 13 | .\" |
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14 | .\" Since the Linux kernel and libraries are constantly changing, this |
15 | .\" manual page may be incorrect or out-of-date. The author(s) assume no | |
16 | .\" responsibility for errors or omissions, or for damages resulting from | |
17 | .\" the use of the information contained herein. The author(s) may not | |
18 | .\" have taken the same level of care in the production of this manual, | |
19 | .\" which is licensed free of charge, as they might when working | |
20 | .\" professionally. | |
c13182ef | 21 | .\" |
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22 | .\" Formatted or processed versions of this manual, if unaccompanied by |
23 | .\" the source, must acknowledge the copyright and authors of this work. | |
24 | .\" | |
50831f9b | 25 | .TH RINT 3 2010-09-20 "" "Linux Programmer's Manual" |
fea681da | 26 | .SH NAME |
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27 | nearbyint, nearbyintf, nearbyintl, rint, rintf, rintl \- round |
28 | to nearest integer | |
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29 | .SH SYNOPSIS |
30 | .nf | |
31 | .B #include <math.h> | |
32 | .sp | |
33 | .BI "double nearbyint(double " x ); | |
34 | .br | |
35 | .BI "float nearbyintf(float " x ); | |
36 | .br | |
37 | .BI "long double nearbyintl(long double " x ); | |
38 | .sp | |
39 | .BI "double rint(double " x ); | |
40 | .br | |
41 | .BI "float rintf(float " x ); | |
42 | .br | |
43 | .BI "long double rintl(long double " x ); | |
44 | .fi | |
45 | .sp | |
20c58d70 | 46 | Link with \fI\-lm\fP. |
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47 | .sp |
48 | .in -4n | |
49 | Feature Test Macro Requirements for glibc (see | |
50 | .BR feature_test_macros (7)): | |
51 | .in | |
52 | .sp | |
53 | .ad l | |
54 | .BR nearbyint (), | |
55 | .BR nearbyintf (), | |
56 | .BR nearbyintl (): | |
27311437 | 57 | .RS 4 |
98dbe7af | 58 | _XOPEN_SOURCE\ >=\ 600 || _POSIX_C_SOURCE\ >=\ 200112L || _ISOC99_SOURCE; |
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59 | .br |
60 | or | |
cc4615cc | 61 | .I cc\ -std=c99 |
27311437 | 62 | .RE |
cc4615cc | 63 | .br |
2517f764 | 64 | .BR rint (): |
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65 | .RS 4 |
66 | _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 500 || | |
67 | _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED || _ISOC99_SOURCE || | |
98dbe7af | 68 | _POSIX_C_SOURCE\ >=\ 200112L; |
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69 | .br |
70 | or | |
2517f764 | 71 | .I cc\ -std=c99 |
27311437 | 72 | .RE |
2517f764 | 73 | .br |
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74 | .BR rintf (), |
75 | .BR rintl (): | |
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76 | .RS 4 |
77 | _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE || | |
98dbe7af | 78 | _POSIX_C_SOURCE\ >=\ 200112L; |
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79 | .br |
80 | or | |
cc4615cc | 81 | .I cc\ -std=c99 |
27311437 | 82 | .RE |
cc4615cc | 83 | .ad b |
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84 | .SH DESCRIPTION |
85 | The | |
e511ffb6 | 86 | .BR nearbyint () |
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87 | functions round their argument to an integer value in floating-point |
88 | format, using the current rounding direction (see | |
89 | .BR fesetround (3)) | |
90 | and without raising the | |
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91 | .I inexact |
92 | exception. | |
93 | .LP | |
94 | The | |
e511ffb6 | 95 | .BR rint () |
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96 | functions do the same, but will raise the |
97 | .I inexact | |
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98 | exception |
99 | .RB ( FE_INEXACT , | |
100 | checkable via | |
101 | .BR fetestexcept (3)) | |
102 | when the result differs in value from the argument. | |
47297adb | 103 | .SH RETURN VALUE |
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104 | These functions return the rounded integer value. |
105 | ||
106 | If \fIx\fP is integral, +0, \-0, NaN, or infinite, | |
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107 | \fIx\fP itself is returned. |
108 | .SH ERRORS | |
2517f764 | 109 | No errors occur. |
efe294cb | 110 | POSIX.1-2001 documents a range error for overflows, but see NOTES. |
47297adb | 111 | .SH CONFORMING TO |
2517f764 | 112 | C99, POSIX.1-2001. |
fea681da | 113 | .SH NOTES |
68e1685c | 114 | SUSv2 and POSIX.1-2001 contain text about overflow (which might set |
fea681da | 115 | .I errno |
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116 | to |
117 | .BR ERANGE , | |
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118 | or raise an |
119 | .B FE_OVERFLOW | |
120 | exception). | |
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121 | In practice, the result cannot overflow on any current machine, |
122 | so this error-handling stuff is just nonsense. | |
123 | (More precisely, overflow can happen only when the maximum value | |
124 | of the exponent is smaller than the number of mantissa bits. | |
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125 | For the IEEE-754 standard 32-bit and 64-bit floating-point numbers |
126 | the maximum value of the exponent is 128 (respectively, 1024), | |
127 | and the number of mantissa bits is 24 (respectively, 53).) | |
128 | ||
129 | If you want to store the rounded value in an integer type, | |
130 | you probably want to use one of the functions described in | |
131 | .BR lrint (3) | |
132 | instead. | |
47297adb | 133 | .SH SEE ALSO |
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134 | .BR ceil (3), |
135 | .BR floor (3), | |
136 | .BR lrint (3), | |
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137 | .BR round (3), |
138 | .BR trunc (3) |