man3/lround.3

   1 .\" Copyright 2001 Andries Brouwer <aeb@cwi.nl>.
   2 .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
   3 .\"     <mtk.manpages@gmail.com>
   4 .\"
   5 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
   6 .\"
   7 .TH LROUND 3 2021-03-22 "Linux man-pages (unreleased)"
   8 .SH NAME
   9 lround, lroundf, lroundl, llround, llroundf, llroundl \- round to
  10 nearest integer
  11 .SH LIBRARY
  12 Math library
  13 .RI ( libm ", " \-lm )
  14 .SH SYNOPSIS
  15 .nf
  16 .B #include <math.h>
  17 .PP
  18 .BI "long lround(double " x );
  19 .BI "long lroundf(float " x );
  20 .BI "long lroundl(long double " x );
  21 .PP
  22 .BI "long long llround(double " x );
  23 .BI "long long llroundf(float " x );
  24 .BI "long long llroundl(long double " x );
  25 .fi
  26 .PP
  27 .RS -4
  28 Feature Test Macro Requirements for glibc (see
  29 .BR feature_test_macros (7)):
  30 .RE
  31 .PP
  32 All functions shown above:
  33 .nf
  34     _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
  35 .fi
  36 .SH DESCRIPTION
  37 These functions round their argument to the nearest integer value,
  38 rounding halfway cases away from zero,
  39 regardless of the current rounding direction (see
  40 .BR fenv (3)).
  41 .PP
  42 Note that unlike the
  43 .BR round (3)
  44 and
  45 .BR ceil (3),
  46 functions, the return type of these functions differs from
  47 that of their arguments.
  48 .SH RETURN VALUE
  49 These functions return the rounded integer value.
  50 .PP
  51 If
  52 .I x
  53 is a NaN or an infinity,
  54 or the rounded value is too large to be stored in a
  55 .I long
  56 .RI ( "long long"
  57 in the case of the
  58 .B ll*
  59 functions),
  60 then a domain error occurs, and the return value is unspecified.
  61 .\" The return value is -(LONG_MAX - 1) or -(LLONG_MAX -1)
  62 .SH ERRORS
  63 See
  64 .BR math_error (7)
  65 for information on how to determine whether an error has occurred
  66 when calling these functions.
  67 .PP
  68 The following errors can occur:
  69 .TP
  70 Domain error: \fIx\fP is a NaN or infinite, or the rounded value is too large
  71 .\" .I errno
  72 .\" is set to
  73 .\" .BR EDOM .
  74 An invalid floating-point exception
  75 .RB ( FE_INVALID )
  76 is raised.
  77 .PP
  78 These functions do not set
  79 .IR errno .
  80 .\" FIXME . Is it intentional that these functions do not set errno?
  81 .\" Bug raised: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6797
  82 .SH VERSIONS
  83 These functions first appeared in glibc in version 2.1.
  84 .SH ATTRIBUTES
  85 For an explanation of the terms used in this section, see
  86 .BR attributes (7).
  87 .ad l
  88 .nh
  89 .TS
  90 allbox;
  91 lbx lb lb
  92 l l l.
  93 Interface       Attribute       Value
  94 T{
  95 .BR lround (),
  96 .BR lroundf (),
  97 .BR lroundl (),
  98 .BR llround (),
  99 .BR llroundf (),
 100 .BR llroundl ()
 101 T}      Thread safety   MT-Safe
 102 .TE
 103 .hy
 104 .ad
 105 .sp 1
 106 .SH STANDARDS
 107 C99, POSIX.1-2001, POSIX.1-2008.
 108 .SH SEE ALSO
 109 .BR ceil (3),
 110 .BR floor (3),
 111 .BR lrint (3),
 112 .BR nearbyint (3),
 113 .BR rint (3),
 114 .BR round (3)