1LRINT(3P) POSIX Programmer's Manual LRINT(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 lrint, lrintf, lrintl — round to nearest integer value using current
13 rounding direction
14
16 #include <math.h>
17 long lrint(double x);
19 long lrintf(float x);
20 long lrintl(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.1‐2017
26 defers to the ISO C standard.
27 These functions shall round their argument to the nearest integer
29 value, rounding according to the current 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 an unspecified value shall be returned. On systems that support the
52 IEC 60559 Floating-Point option, a domain error shall occur; otherwise,
53 a domain error may occur.
54 If the correct value is negative and too large to represent as a long,
56 an unspecified value shall be returned. On systems that support the
57 IEC 60559 Floating-Point option, a domain error shall occur; otherwise,
58 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 provide floating-to-integer conversions. They round
96 according to the current rounding direction. If the rounded value is
97 outside the range of the return type, the numeric result is unspecified
98 and the invalid floating-point exception is raised. When they raise no
99 other floating-point exception and the result differs from the argu‐
100 ment, they raise the inexact floating-point exception.
101
103 None.
104
106 feclearexcept(), fetestexcept(), llrint()
107 The Base Definitions volume of POSIX.1‐2017, Section 4.20, Treatment of
109 Error Conditions for Mathematical Functions, <math.h>
110
112 Portions of this text are reprinted and reproduced in electronic form
113 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
114 table Operating System Interface (POSIX), The Open Group Base Specifi‐
115 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
116 Electrical and Electronics Engineers, Inc and The Open Group. In the
117 event of any discrepancy between this version and the original IEEE and
118 The Open Group Standard, the original IEEE and The Open Group Standard
119 is the referee document. The original Standard can be obtained online
120 at http://www.opengroup.org/unix/online.html .
121 Any typographical or formatting errors that appear in this page are
123 most likely to have been introduced during the conversion of the source
124 files to man page format. To report such errors, see https://www.ker‐
125 nel.org/doc/man-pages/reporting_bugs.html .
126IEEE/The Open Group 2017 LRINT(3P)