man3/nextup.3

   1 .\" Copyright (C) 2016, Michael Kerrisk <mtk.manpages@gmail.com>
   2 .\"
   3 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
   4 .\"
   5 .TH NEXTUP 3 2021-03-22 "Linux man-pages (unreleased)" "Linux Programmer's Manual"
   6 .SH NAME
   7 nextup, nextupf, nextupl, nextdown, nextdownf, nextdownl \-
   8 return next floating-point number toward positive/negative infinity
   9 .SH LIBRARY
  10 Math library
  11 .RI ( libm ", " \-lm )
  12 .SH SYNOPSIS
  13 .nf
  14 .BR "#define _GNU_SOURCE" "     /* See feature_test_macros(7) */"
  15 .B #include <math.h>
  16 .PP
  17 .BI "double nextup(double " x );
  18 .BI "float nextupf(float " x );
  19 .BI "long double nextupl(long double " x );
  20 .PP
  21 .BI "double nextdown(double " x );
  22 .BI "float nextdownf(float " x );
  23 .BI "long double nextdownl(long double " x );
  24 .fi
  25 .SH DESCRIPTION
  26 The
  27 .BR nextup (),
  28 .BR nextupf (),
  29 and
  30 .BR nextupl ()
  31 functions return the next representable floating-point number greater than
  32 .IR x .
  33 .PP
  34 If
  35 .I x
  36 is the smallest representable negative number in the corresponding type,
  37 these functions return \-0.
  38 If
  39 .I x
  40 is 0, the returned value is the smallest representable positive number
  41 of the corresponding type.
  42 .PP
  43 If
  44 .I x
  45 is positive infinity, the returned value is positive infinity.
  46 If
  47 .I x
  48 is negative infinity,
  49 the returned value is the largest representable finite negative number
  50 of the corresponding type.
  51 .PP
  52 If
  53 .I x
  54 is Nan,
  55 the returned value is NaN.
  56 .PP
  57 The value returned by
  58 .I nextdown(x)
  59 is
  60 .IR \-nextup(\-x) ,
  61 and similarly for the other types.
  62 .SH RETURN VALUE
  63 See DESCRIPTION.
  64 .\" .SH ERRORS
  65 .SH VERSIONS
  66 These functions first appeared in glibc in version 2.24.
  67 .SH ATTRIBUTES
  68 For an explanation of the terms used in this section, see
  69 .BR attributes (7).
  70 .ad l
  71 .nh
  72 .TS
  73 allbox;
  74 lbx lb lb
  75 l l l.
  76 Interface       Attribute       Value
  77 T{
  78 .BR nextup (),
  79 .BR nextupf (),
  80 .BR nextupl (),
  81 .BR nextdown (),
  82 .BR nextdownf (),
  83 .BR nextdownl ()
  84 T}      Thread safety   MT-Safe
  85 .TE
  86 .hy
  87 .ad
  88 .sp 1
  89 .SH STANDARDS
  90 These functions are described in
  91 .I IEEE Std 754-2008 - Standard for Floating-Point Arithmetic
  92 and
  93 .IR "ISO/IEC TS 18661".
  94 .SH SEE ALSO
  95 .BR nearbyint (3),
  96 .BR nextafter (3)