1RINT(3P) POSIX Programmer's Manual RINT(3P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
13 rint, rintf, rintl — round-to-nearest integral value
14
16 #include <math.h>
17 double rint(double x);
19 float rintf(float x);
20 long double rintl(long double x);
21
23 The functionality described on this reference page is aligned with the
24 ISO C standard. Any conflict between the requirements described here
25 and the ISO C standard is unintentional. This volume of POSIX.1‐2008
26 defers to the ISO C standard.
27 These functions shall return the integral value (represented as a dou‐
29 ble) nearest x in the direction of the current rounding mode. The cur‐
30 rent rounding mode is implementation-defined.
31 If the current rounding mode rounds toward negative infinity, then
33 rint() shall be equivalent to floor(). If the current rounding mode
34 rounds toward positive infinity, then rint() shall be equivalent to
35 ceil(). If the current rounding mode rounds towards zero, then rint()
36 shall be equivalent to trunc(). If the current rounding mode rounds
37 towards nearest, then rint() differs from round() in that halfway cases
38 are rounded to even rather than away from zero.
39 These functions differ from the nearbyint(), nearbyintf(), and nearby‐
41 intl() functions only in that they may raise the inexact floating-point
42 exception if the result differs in value from the argument.
43 An application wishing to check for error situations should set errno
45 to zero and call feclearexcept(FE_ALL_EXCEPT) before calling these
46 functions. On return, if errno is non-zero or fetestexcept(FE_INVALID |
47 FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has
48 occurred.
49
51 Upon successful completion, these functions shall return the integer
52 (represented as a double precision number) nearest x in the direction
53 of the current rounding mode. The result shall have the same sign as
54 x.
55 If x is NaN, a NaN shall be returned.
57 If x is ±0 or ±Inf, x shall be returned.
59
61 No errors are defined.
62 The following sections are informative.
64
66 None.
67
69 The integral value returned by these functions need not be expressible
70 as an intmax_t. The return value should be tested before assigning it
71 to an integer type to avoid the undefined results of an integer over‐
72 flow.
73
75 None.
76
78 None.
79
81 abs(), ceil(), feclearexcept(), fetestexcept(), floor(), isnan(), near‐
82 byint()
83 The Base Definitions volume of POSIX.1‐2008, Section 4.19, Treatment of
85 Error Conditions for Mathematical Functions, <math.h>
86
88 Portions of this text are reprinted and reproduced in electronic form
89 from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
90 -- Portable Operating System Interface (POSIX), The Open Group Base
91 Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
92 cal and Electronics Engineers, Inc and The Open Group. (This is
93 POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
94 event of any discrepancy between this version and the original IEEE and
95 The Open Group Standard, the original IEEE and The Open Group Standard
96 is the referee document. The original Standard can be obtained online
97 at http://www.unix.org/online.html .
98 Any typographical or formatting errors that appear in this page are
100 most likely to have been introduced during the conversion of the source
101 files to man page format. To report such errors, see https://www.ker‐
102 nel.org/doc/man-pages/reporting_bugs.html .
103IEEE/The Open Group 2013 RINT(3P)