man3/lround.3

   1 .\" Copyright 2001 Andries Brouwer <aeb@cwi.nl>.
   2 .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
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  27 .TH LROUND 3  2017-09-15 "" "Linux Programmer's Manual"
  28 .SH NAME
  29 lround, lroundf, lroundl, llround, llroundf, llroundl \- round to
  30 nearest integer
  31 .SH SYNOPSIS
  32 .nf
  33 .B #include <math.h>
  34 .PP
  35 .BI "long int lround(double " x );
  36 .BI "long int lroundf(float " x );
  37 .BI "long int lroundl(long double " x );
  38 .PP
  39 .BI "long long int llround(double " x );
  40 .BI "long long int llroundf(float " x );
  41 .BI "long long int llroundl(long double " x );
  42 .fi
  43 .PP
  44 Link with \fI\-lm\fP.
  45 .PP
  46 .in -4n
  47 Feature Test Macro Requirements for glibc (see
  48 .BR feature_test_macros (7)):
  49 .in
  50 .PP
  51 .ad l
  52 All functions shown above:
  53 .RS 4
  54 _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
  55 .RE
  56 .ad
  57 .SH DESCRIPTION
  58 These functions round their argument to the nearest integer value,
  59 rounding halfway cases away from zero,
  60 regardless of the current rounding direction (see
  61 .BR fenv (3)).
  62 .PP
  63 Note that unlike the
  64 .BR round (3)
  65 and
  66 .BR ceil (3),
  67 functions, the return type of these functions differs from
  68 that of their arguments.
  69 .SH RETURN VALUE
  70 These functions return the rounded integer value.
  71 .PP
  72 If
  73 .I x
  74 is a NaN or an infinity,
  75 or the rounded value is too large to be stored in a
  76 .I long
  77 .RI ( "long long"
  78 in the case of the
  79 .B ll*
  80 functions),
  81 then a domain error occurs, and the return value is unspecified.
  82 .\" The return value is -(LONG_MAX - 1) or -(LLONG_MAX -1)
  83 .SH ERRORS
  84 See
  85 .BR math_error (7)
  86 for information on how to determine whether an error has occurred
  87 when calling these functions.
  88 .PP
  89 The following errors can occur:
  90 .TP
  91 Domain error: \fIx\fP is a NaN or infinite, or the rounded value is too large
  92 .\" .I errno
  93 .\" is set to
  94 .\" .BR EDOM .
  95 An invalid floating-point exception
  96 .RB ( FE_INVALID )
  97 is raised.
  98 .PP
  99 These functions do not set
 100 .IR errno .
 101 .\" FIXME . Is it intentional that these functions do not set errno?
 102 .\" Bug raised: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6797
 103 .SH VERSIONS
 104 These functions first appeared in glibc in version 2.1.
 105 .SH ATTRIBUTES
 106 For an explanation of the terms used in this section, see
 107 .BR attributes (7).
 108 .TS
 109 allbox;
 110 lbw33 lb lb
 111 l l l.
 112 Interface       Attribute       Value
 113 T{
 114 .BR lround (),
 115 .BR lroundf (),
 116 .BR lroundl (),
 117 .br
 118 .BR llround (),
 119 .BR llroundf (),
 120 .BR llroundl ()
 121 T}      Thread safety   MT-Safe
 122 .TE
 123 .SH CONFORMING TO
 124 C99, POSIX.1-2001, POSIX.1-2008.
 125 .SH SEE ALSO
 126 .BR ceil (3),
 127 .BR floor (3),
 128 .BR lrint (3),
 129 .BR nearbyint (3),
 130 .BR rint (3),
 131 .BR round (3)