man3/lround.3

   1 '\" t
   2 .\" Copyright 2001 Andries Brouwer <aeb@cwi.nl>.
   3 .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
   4 .\"     <mtk.manpages@gmail.com>
   5 .\"
   6 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
   7 .\"
   8 .TH lround 3 (date) "Linux man-pages (unreleased)"
   9 .SH NAME
  10 lround, lroundf, lroundl, llround, llroundf, llroundl \- round to
  11 nearest integer
  12 .SH LIBRARY
  13 Math library
  14 .RI ( libm ", " \-lm )
  15 .SH SYNOPSIS
  16 .nf
  17 .B #include <math.h>
  18 .P
  19 .BI "long lround(double " x );
  20 .BI "long lroundf(float " x );
  21 .BI "long lroundl(long double " x );
  22 .P
  23 .BI "long long llround(double " x );
  24 .BI "long long llroundf(float " x );
  25 .BI "long long llroundl(long double " x );
  26 .fi
  27 .P
  28 .RS -4
  29 Feature Test Macro Requirements for glibc (see
  30 .BR feature_test_macros (7)):
  31 .RE
  32 .P
  33 All functions shown above:
  34 .nf
  35     _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
  36 .fi
  37 .SH DESCRIPTION
  38 These functions round their argument to the nearest integer value,
  39 rounding halfway cases away from zero,
  40 regardless of the current rounding direction (see
  41 .BR fenv (3)).
  42 .P
  43 Note that unlike the
  44 .BR round (3)
  45 and
  46 .BR ceil (3),
  47 functions, the return type of these functions differs from
  48 that of their arguments.
  49 .SH RETURN VALUE
  50 These functions return the rounded integer value.
  51 .P
  52 If
  53 .I x
  54 is a NaN or an infinity,
  55 or the rounded value is too large to be stored in a
  56 .I long
  57 .RI ( "long long"
  58 in the case of the
  59 .B ll*
  60 functions),
  61 then a domain error occurs, and the return value is unspecified.
  62 .\" The return value is -(LONG_MAX - 1) or -(LLONG_MAX -1)
  63 .SH ERRORS
  64 See
  65 .BR math_error (7)
  66 for information on how to determine whether an error has occurred
  67 when calling these functions.
  68 .P
  69 The following errors can occur:
  70 .TP
  71 Domain error: \fIx\fP is a NaN or infinite, or the rounded value is too large
  72 .\" .I errno
  73 .\" is set to
  74 .\" .BR EDOM .
  75 An invalid floating-point exception
  76 .RB ( FE_INVALID )
  77 is raised.
  78 .P
  79 These functions do not set
  80 .IR errno .
  81 .\" FIXME . Is it intentional that these functions do not set errno?
  82 .\" Bug raised: https://www.sourceware.org/bugzilla/show_bug.cgi?id=6797
  83 .SH ATTRIBUTES
  84 For an explanation of the terms used in this section, see
  85 .BR attributes (7).
  86 .TS
  87 allbox;
  88 lbx lb lb
  89 l l l.
  90 Interface       Attribute       Value
  91 T{
  92 .na
  93 .nh
  94 .BR lround (),
  95 .BR lroundf (),
  96 .BR lroundl (),
  97 .BR llround (),
  98 .BR llroundf (),
  99 .BR llroundl ()
 100 T}      Thread safety   MT-Safe
 101 .TE
 102 .SH STANDARDS
 103 C11, POSIX.1-2008.
 104 .SH HISTORY
 105 glibc 2.1.
 106 C99, POSIX.1-2001.
 107 .SH SEE ALSO
 108 .BR ceil (3),
 109 .BR floor (3),
 110 .BR lrint (3),
 111 .BR nearbyint (3),
 112 .BR rint (3),
 113 .BR round (3)