1LLROUND(3P) POSIX Programmer's Manual LLROUND(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
12 llround, llroundf, llroundl — round to nearest integer value
13
15 #include <math.h>
16 long long llround(double x);
18 long long llroundf(float x);
19 long long llroundl(long double x);
20
22 The functionality described on this reference page is aligned with the
23 ISO C standard. Any conflict between the requirements described here
24 and the ISO C standard is unintentional. This volume of POSIX.1‐2017
25 defers to the ISO C standard.
26 These functions shall round their argument to the nearest integer
28 value, rounding halfway cases away from zero, regardless of the current
29 rounding direction.
30 An application wishing to check for error situations should set errno
32 to zero and call feclearexcept(FE_ALL_EXCEPT) before calling these
33 functions. On return, if errno is non-zero or fetestexcept(FE_INVALID |
34 FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has
35 occurred.
36
38 Upon successful completion, these functions shall return the rounded
39 integer value.
40 If x is NaN, a domain error shall occur, and an unspecified value is
42 returned.
43 If x is +Inf, a domain error shall occur and an unspecified value is
45 returned.
46 If x is -Inf, a domain error shall occur and an unspecified value is
48 returned.
49 If the correct value is positive and too large to represent as a long
51 long, an unspecified value shall be returned. On systems that support
52 the IEC 60559 Floating-Point option, a domain error shall occur; other‐
53 wise, a domain error may occur.
54 If the correct value is negative and too large to represent as a long
56 long, an unspecified value shall be returned. On systems that support
57 the IEC 60559 Floating-Point option, a domain error shall occur; other‐
58 wise, a domain error may occur.
59
61 These functions shall fail if:
62 Domain Error
64 The x argument is NaN or ±Inf, or the correct value is not
65 representable as an integer.
66 If the integer expression (math_errhandling & MATH_ERRNO)
68 is non-zero, then errno shall be set to [EDOM]. If the
69 integer expression (math_errhandling & MATH_ERREXCEPT) is
70 non-zero, then the invalid floating-point exception shall
71 be raised.
72 These functions may fail if:
74 Domain Error
76 The correct value is not representable as an integer.
77 If the integer expression (math_errhandling & MATH_ERRNO)
79 is non-zero, then errno shall be set to [EDOM]. If the
80 integer expression (math_errhandling & MATH_ERREXCEPT) is
81 non-zero, then the invalid floating-point exception shall
82 be raised.
83 The following sections are informative.
85
87 None.
88
90 On error, the expressions (math_errhandling & MATH_ERRNO) and
91 (math_errhandling & MATH_ERREXCEPT) are independent of each other, but
92 at least one of them must be non-zero.
93
95 These functions differ from the llrint() functions in that the default
96 rounding direction for the llround() functions round halfway cases away
97 from zero and need not raise the inexact floating-point exception for
98 non-integer arguments that round to within the range of the return
99 type.
100
102 None.
103
105 feclearexcept(), fetestexcept(), lround()
106 The Base Definitions volume of POSIX.1‐2017, Section 4.20, Treatment of
108 Error Conditions for Mathematical Functions, <math.h>
109
111 Portions of this text are reprinted and reproduced in electronic form
112 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
113 table Operating System Interface (POSIX), The Open Group Base Specifi‐
114 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
115 Electrical and Electronics Engineers, Inc and The Open Group. In the
116 event of any discrepancy between this version and the original IEEE and
117 The Open Group Standard, the original IEEE and The Open Group Standard
118 is the referee document. The original Standard can be obtained online
119 at http://www.opengroup.org/unix/online.html .
120 Any typographical or formatting errors that appear in this page are
122 most likely to have been introduced during the conversion of the source
123 files to man page format. To report such errors, see https://www.ker‐
124 nel.org/doc/man-pages/reporting_bugs.html .
125IEEE/The Open Group 2017 LLROUND(3P)