1 .\" Copyright 2001 Andries Brouwer <aeb@cwi.nl>.
2 .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
3 .\" <mtk.manpages@gmail.com>
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25 .TH RINT 3 2008-08-05 "" "Linux Programmer's Manual"
27 nearbyint, nearbyintf, nearbyintl, rint, rintf, rintl \- round
33 .BI "double nearbyint(double " x );
35 .BI "float nearbyintf(float " x );
37 .BI "long double nearbyintl(long double " x );
39 .BI "double rint(double " x );
41 .BI "float rintf(float " x );
43 .BI "long double rintl(long double " x );
49 Feature Test Macro Requirements for glibc (see
50 .BR feature_test_macros (7)):
57 _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE; or
61 _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 500 || _ISOC99_SOURCE; or
66 _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE; or
72 functions round their argument to an integer value in floating-point
73 format, using the current rounding direction (see
75 and without raising the
81 functions do the same, but will raise the
87 when the result differs in value from the argument.
89 These functions return the rounded integer value.
91 If \fIx\fP is integral, +0, \-0, NaN, or infinite,
92 \fIx\fP itself is returned.
95 POSIX.1-2001 documents a range error for overflows, but see NOTES.
99 SUSv2 and POSIX.1-2001 contain text about overflow (which might set
106 In practice, the result cannot overflow on any current machine,
107 so this error-handling stuff is just nonsense.
108 (More precisely, overflow can happen only when the maximum value
109 of the exponent is smaller than the number of mantissa bits.
110 For the IEEE-754 standard 32-bit and 64-bit floating-point numbers
111 the maximum value of the exponent is 128 (respectively, 1024),
112 and the number of mantissa bits is 24 (respectively, 53).)
114 If you want to store the rounded value in an integer type,
115 you probably want to use one of the functions described in