man3/scalbln.3

   1 '\" t
   2 .\" Copyright 2004 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 scalbln 3 (date) "Linux man-pages (unreleased)"
   9 .SH NAME
  10 scalbn, scalbnf, scalbnl, scalbln, scalblnf, scalblnl \-
  11 multiply floating-point number by integral power of radix
  12 .SH LIBRARY
  13 Math library
  14 .RI ( libm ", " \-lm )
  15 .SH SYNOPSIS
  16 .nf
  17 .B #include <math.h>
  18 .PP
  19 .BI "double scalbln(double " x ", long " exp );
  20 .BI "float scalblnf(float " x ", long " exp );
  21 .BI "long double scalblnl(long double " x ", long " exp );
  22 .PP
  23 .BI "double scalbn(double " x ", int " exp );
  24 .BI "float scalbnf(float " x ", int " exp );
  25 .BI "long double scalbnl(long double " x ", int " exp );
  26 .fi
  27 .PP
  28 .RS -4
  29 Feature Test Macro Requirements for glibc (see
  30 .BR feature_test_macros (7)):
  31 .RE
  32 .PP
  33 .BR scalbln (),
  34 .BR scalblnf (),
  35 .BR scalblnl ():
  36 .nf
  37     _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
  38         || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  39 .fi
  40 .PP
  41 .BR scalbn (),
  42 .BR scalbnf (),
  43 .BR scalbnl ():
  44 .nf
  45     _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
  46         || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  47         || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
  48 .fi
  49 .SH DESCRIPTION
  50 These functions multiply their first argument
  51 .I x
  52 by
  53 .B FLT_RADIX
  54 (probably 2)
  55 to the power of
  56 .IR exp ,
  57 that is:
  58 .PP
  59 .nf
  60     x * FLT_RADIX ** exp
  61 .fi
  62 .PP
  63 The definition of
  64 .B FLT_RADIX
  65 can be obtained by including
  66 .IR <float.h> .
  67 .\" not in /usr/include but in a gcc lib
  68 .SH RETURN VALUE
  69 On success, these functions return
  70 .I x
  71 *
  72 .B FLT_RADIX
  73 **
  74 .IR exp .
  75 .PP
  76 If
  77 .I x
  78 is a NaN, a NaN is returned.
  79 .PP
  80 If
  81 .I x
  82 is positive infinity (negative infinity),
  83 positive infinity (negative infinity) is returned.
  84 .PP
  85 If
  86 .I x
  87 is +0 (\-0), +0 (\-0) is returned.
  88 .PP
  89 If the result overflows,
  90 a range error occurs,
  91 and the functions return
  92 .BR HUGE_VAL ,
  93 .BR HUGE_VALF ,
  94 or
  95 .BR HUGE_VALL ,
  96 respectively, with a sign the same as
  97 .IR x .
  98 .PP
  99 If the result underflows,
 100 a range error occurs,
 101 and the functions return zero, with a sign the same as
 102 .IR x .
 103 .SH ERRORS
 104 See
 105 .BR math_error (7)
 106 for information on how to determine whether an error has occurred
 107 when calling these functions.
 108 .PP
 109 The following errors can occur:
 110 .TP
 111 Range error, overflow
 112 .\" .I errno
 113 .\" is set to
 114 .\" .BR ERANGE .
 115 An overflow floating-point exception
 116 .RB ( FE_OVERFLOW )
 117 is raised.
 118 .TP
 119 Range error, underflow
 120 .I errno
 121 is set to
 122 .BR ERANGE .
 123 An underflow floating-point exception
 124 .RB ( FE_UNDERFLOW )
 125 is raised.
 126 .SH ATTRIBUTES
 127 For an explanation of the terms used in this section, see
 128 .BR attributes (7).
 129 .ad l
 130 .nh
 131 .TS
 132 allbox;
 133 lbx lb lb
 134 l l l.
 135 Interface       Attribute       Value
 136 T{
 137 .BR scalbn (),
 138 .BR scalbnf (),
 139 .BR scalbnl (),
 140 .BR scalbln (),
 141 .BR scalblnf (),
 142 .BR scalblnl ()
 143 T}      Thread safety   MT-Safe
 144 .TE
 145 .hy
 146 .ad
 147 .sp 1
 148 .SH STANDARDS
 149 C11, POSIX.1-2008.
 150 .SH HISTORY
 151 glibc 2.1.
 152 C99, POSIX.1-2001.
 153 .SH HISTORY
 154 These functions differ from the obsolete functions described in
 155 .BR scalb (3)
 156 in the type of their second argument.
 157 The functions described on this page have a second argument
 158 of an integral type, while those in
 159 .BR scalb (3)
 160 have a second argument of type
 161 .IR double .
 162 .SH NOTES
 163 If
 164 .B FLT_RADIX
 165 equals 2 (which is usual), then
 166 .BR scalbn ()
 167 is equivalent to
 168 .BR ldexp (3).
 169 .SH BUGS
 170 Before glibc 2.20,
 171 .\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6803
 172 these functions did not set
 173 .I errno
 174 for range errors.
 175 .SH SEE ALSO
 176 .BR ldexp (3),
 177 .BR scalb (3)