man3/rint.3

   1 .\" Copyright 2001 Andries Brouwer <aeb@cwi.nl>.
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  23 .TH RINT 3  2001-05-31 "" "Linux Programmer's Manual"
  24 .SH NAME
  25 nearbyint, nearbyintf, nearbyintl, rint, rintf, rintl \- round to nearest integer
  26 .SH SYNOPSIS
  27 .nf
  28 .B #include <math.h>
  29 .sp
  30 .BI "double nearbyint(double " x );
  31 .br
  32 .BI "float nearbyintf(float " x );
  33 .br
  34 .BI "long double nearbyintl(long double " x );
  35 .sp
  36 .BI "double rint(double " x );
  37 .br
  38 .BI "float rintf(float " x );
  39 .br
  40 .BI "long double rintl(long double " x );
  41 .fi
  42 .sp
  43 Link with \fI-lm\fP.
  44 .SH DESCRIPTION
  45 The
  46 .BR nearbyint ()
  47 functions round their argument to an integer value in floating point
  48 format, using the current rounding direction and without raising the
  49 .I inexact
  50 exception.
  51 .LP
  52 The
  53 .BR rint ()
  54 functions do the same, but will raise the
  55 .I inexact
  56 exception when the result differs in value from the argument.
  57 .SH "RETURN VALUE"
  58 The rounded integer value.
  59 If \fIx\fP is integral or infinite,
  60 \fIx\fP itself is returned.
  61 .SH ERRORS
  62 No errors other than
  63 .B EDOM
  64 and
  65 .B ERANGE
  66 can occur.
  67 If \fIx\fP is NaN, then NaN is returned and
  68 .I errno
  69 may be set to
  70 .BR EDOM .
  71 .SH "CONFORMING TO"
  72 C99.
  73 .SH NOTES
  74 SUSv2 and POSIX.1-2001 contain text about overflow (which might set
  75 .I errno
  76 to
  77 .BR ERANGE ,
  78 or raise an exception).
  79 In practice, the result cannot overflow on any current machine,
  80 so this error-handling stuff is just nonsense.
  81 (More precisely, overflow can happen only when the maximum value
  82 of the exponent is smaller than the number of mantissa bits.
  83 For the IEEE-754 standard 32-bit and 64-bit floating point numbers
  84 the maximum value of the exponent is 128 (resp. 1024), and the number
  85 of mantissa bits is 24 (resp. 53).)
  86 .SH "SEE ALSO"
  87 .BR ceil (3),
  88 .BR floor (3),
  89 .BR lrint (3),
  90 .BR nearbyint (3),
  91 .BR round (3),
  92 .BR trunc (3)