man3/scalbln.3

   1 .\" Copyright 2004 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 SCALBLN 3 2021-03-22 "Linux man-pages (unreleased)"
   8 .SH NAME
   9 scalbn, scalbnf, scalbnl, scalbln, scalblnf, scalblnl \-
  10 multiply floating-point number by integral power of radix
  11 .SH LIBRARY
  12 Math library
  13 .RI ( libm ", " \-lm )
  14 .SH SYNOPSIS
  15 .nf
  16 .B #include <math.h>
  17 .PP
  18 .BI "double scalbln(double " x ", long " exp );
  19 .BI "float scalblnf(float " x ", long " exp );
  20 .BI "long double scalblnl(long double " x ", long " exp );
  21 .PP
  22 .BI "double scalbn(double " x ", int " exp );
  23 .BI "float scalbnf(float " x ", int " exp );
  24 .BI "long double scalbnl(long double " x ", int " exp );
  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 .BR scalbln (),
  33 .BR scalblnf (),
  34 .BR scalblnl ():
  35 .nf
  36     _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
  37         || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  38 .fi
  39 .PP
  40 .BR scalbn (),
  41 .BR scalbnf (),
  42 .BR scalbnl ():
  43 .nf
  44     _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
  45         || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  46         || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
  47 .fi
  48 .SH DESCRIPTION
  49 These functions multiply their first argument
  50 .I x
  51 by
  52 .B FLT_RADIX
  53 (probably 2)
  54 to the power of
  55 .IR exp ,
  56 that is:
  57 .PP
  58 .nf
  59     x * FLT_RADIX ** exp
  60 .fi
  61 .PP
  62 The definition of
  63 .B FLT_RADIX
  64 can be obtained by including
  65 .IR <float.h> .
  66 .\" not in /usr/include but in a gcc lib
  67 .SH RETURN VALUE
  68 On success, these functions return
  69 .I x
  70 *
  71 .B FLT_RADIX
  72 **
  73 .IR exp .
  74 .PP
  75 If
  76 .I x
  77 is a NaN, a NaN is returned.
  78 .PP
  79 If
  80 .I x
  81 is positive infinity (negative infinity),
  82 positive infinity (negative infinity) is returned.
  83 .PP
  84 If
  85 .I x
  86 is +0 (\-0), +0 (\-0) is returned.
  87 .PP
  88 If the result overflows,
  89 a range error occurs,
  90 and the functions return
  91 .BR HUGE_VAL ,
  92 .BR HUGE_VALF ,
  93 or
  94 .BR HUGE_VALL ,
  95 respectively, with a sign the same as
  96 .IR x .
  97 .PP
  98 If the result underflows,
  99 a range error occurs,
 100 and the functions return zero, with a sign the same as
 101 .IR x .
 102 .SH ERRORS
 103 See
 104 .BR math_error (7)
 105 for information on how to determine whether an error has occurred
 106 when calling these functions.
 107 .PP
 108 The following errors can occur:
 109 .TP
 110 Range error, overflow
 111 .\" .I errno
 112 .\" is set to
 113 .\" .BR ERANGE .
 114 An overflow floating-point exception
 115 .RB ( FE_OVERFLOW )
 116 is raised.
 117 .TP
 118 Range error, underflow
 119 .I errno
 120 is set to
 121 .BR ERANGE .
 122 An underflow floating-point exception
 123 .RB ( FE_UNDERFLOW )
 124 is raised.
 125 .SH VERSIONS
 126 These functions first appeared in glibc in version 2.1.
 127 .SH ATTRIBUTES
 128 For an explanation of the terms used in this section, see
 129 .BR attributes (7).
 130 .ad l
 131 .nh
 132 .TS
 133 allbox;
 134 lbx lb lb
 135 l l l.
 136 Interface       Attribute       Value
 137 T{
 138 .BR scalbn (),
 139 .BR scalbnf (),
 140 .BR scalbnl (),
 141 .BR scalbln (),
 142 .BR scalblnf (),
 143 .BR scalblnl ()
 144 T}      Thread safety   MT-Safe
 145 .TE
 146 .hy
 147 .ad
 148 .sp 1
 149 .SH STANDARDS
 150 C99, POSIX.1-2001, POSIX.1-2008.
 151 .SH NOTES
 152 These functions differ from the obsolete functions described in
 153 .BR scalb (3)
 154 in the type of their second argument.
 155 The functions described on this page have a second argument
 156 of an integral type, while those in
 157 .BR scalb (3)
 158 have a second argument of type
 159 .IR double .
 160 .PP
 161 If
 162 .B FLT_RADIX
 163 equals 2 (which is usual), then
 164 .BR scalbn ()
 165 is equivalent to
 166 .BR ldexp (3).
 167 .SH BUGS
 168 Before glibc 2.20,
 169 .\" http://sources.redhat.com/bugzilla/show_bug.cgi?id=6803
 170 these functions did not set
 171 .I errno
 172 for range errors.
 173 .SH SEE ALSO
 174 .BR ldexp (3),
 175 .BR scalb (3)