man3/scalb.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 scalb 3 (date) "Linux man-pages (unreleased)"
   9 .SH NAME
  10 scalb, scalbf, scalbl \- multiply floating-point number
  11 by integral power of radix (OBSOLETE)
  12 .SH LIBRARY
  13 Math library
  14 .RI ( libm ", " \-lm )
  15 .SH SYNOPSIS
  16 .nf
  17 .B #include <math.h>
  18 .PP
  19 .BI "[[deprecated]] double scalb(double " x ", double " exp );
  20 .BI "[[deprecated]] float scalbf(float " x ", float " exp );
  21 .BI "[[deprecated]] long double scalbl(long double " x ", long double " exp );
  22 .fi
  23 .PP
  24 .RS -4
  25 Feature Test Macro Requirements for glibc (see
  26 .BR feature_test_macros (7)):
  27 .RE
  28 .PP
  29 .BR scalb ():
  30 .nf
  31     _XOPEN_SOURCE >= 500
  32 .\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
  33         || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  34         || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
  35 .fi
  36 .PP
  37 .BR scalbf (),
  38 .BR scalbl ():
  39 .nf
  40     _XOPEN_SOURCE >= 600
  41         || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  42         || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
  43 .fi
  44 .SH DESCRIPTION
  45 These functions multiply their first argument
  46 .I x
  47 by
  48 .B FLT_RADIX
  49 (probably 2)
  50 to the power of
  51 .IR exp ,
  52 that is:
  53 .PP
  54 .nf
  55     x * FLT_RADIX ** exp
  56 .fi
  57 .PP
  58 The definition of
  59 .B FLT_RADIX
  60 can be obtained by including
  61 .IR <float.h> .
  62 .\" not in /usr/include but in a gcc lib
  63 .SH RETURN VALUE
  64 On success, these functions return
  65 .I x
  66 *
  67 .B FLT_RADIX
  68 **
  69 .IR exp .
  70 .PP
  71 If
  72 .I x
  73 or
  74 .I exp
  75 is a NaN, a NaN is returned.
  76 .PP
  77 If
  78 .I x
  79 is positive infinity (negative infinity),
  80 and
  81 .I exp
  82 is not negative infinity,
  83 positive infinity (negative infinity) is returned.
  84 .PP
  85 If
  86 .I x
  87 is +0 (\-0), and
  88 .I exp
  89 is not positive infinity, +0 (\-0) is returned.
  90 .PP
  91 If
  92 .I x
  93 is zero, and
  94 .I exp
  95 is positive infinity,
  96 a domain error occurs, and
  97 a NaN is returned.
  98 .PP
  99 If
 100 .I x
 101 is an infinity,
 102 and
 103 .I exp
 104 is negative infinity,
 105 a domain error occurs, and
 106 a NaN is returned.
 107 .PP
 108 If the result overflows,
 109 a range error occurs,
 110 and the functions return
 111 .BR HUGE_VAL ,
 112 .BR HUGE_VALF ,
 113 or
 114 .BR HUGE_VALL ,
 115 respectively, with a sign the same as
 116 .IR x .
 117 .PP
 118 If the result underflows,
 119 a range error occurs,
 120 and the functions return zero, with a sign the same as
 121 .IR x .
 122 .SH ERRORS
 123 See
 124 .BR math_error (7)
 125 for information on how to determine whether an error has occurred
 126 when calling these functions.
 127 .PP
 128 The following errors can occur:
 129 .TP
 130 Domain error: \fIx\fP is 0, and \fIexp\fP is positive infinity, \
 131 or \fIx\fP is positive infinity and \fIexp\fP is negative infinity \
 132 and the other argument is not a NaN
 133 .I errno
 134 is set to
 135 .BR EDOM .
 136 An invalid floating-point exception
 137 .RB ( FE_INVALID )
 138 is raised.
 139 .TP
 140 Range error, overflow
 141 .I errno
 142 is set to
 143 .BR ERANGE .
 144 An overflow floating-point exception
 145 .RB ( FE_OVERFLOW )
 146 is raised.
 147 .TP
 148 Range error, underflow
 149 .I errno
 150 is set to
 151 .BR ERANGE .
 152 An underflow floating-point exception
 153 .RB ( FE_UNDERFLOW )
 154 is raised.
 155 .SH ATTRIBUTES
 156 For an explanation of the terms used in this section, see
 157 .BR attributes (7).
 158 .ad l
 159 .nh
 160 .TS
 161 allbox;
 162 lbx lb lb
 163 l l l.
 164 Interface       Attribute       Value
 165 T{
 166 .BR scalb (),
 167 .BR scalbf (),
 168 .BR scalbl ()
 169 T}      Thread safety   MT-Safe
 170 .TE
 171 .hy
 172 .ad
 173 .sp 1
 174 .SH STANDARDS
 175 None.
 176 .SH HISTORY
 177 .TP
 178 .BR scalb ()
 179 4.3BSD.
 180 Obsolescent in POSIX.1-2001;
 181 Removed in POSIX.1-2008,
 182 recommending the use of
 183 .BR scalbln (3),
 184 .BR scalblnf (3),
 185 or
 186 .BR scalblnl (3)
 187 instead.
 188 .\" Looking at header files: scalbf() is present on the
 189 .\" BSDs, Tru64, HP-UX 11, Irix 6.5; scalbl() is on HP-UX 11 and Tru64.
 190 .SH BUGS
 191 Before glibc 2.20,
 192 .\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6803
 193 .\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6804
 194 these functions did not set
 195 .I errno
 196 for domain and range errors.
 197 .SH SEE ALSO
 198 .BR ldexp (3),
 199 .BR scalbln (3)