man3/scalb.3

   1 .\" Copyright 2004 Andries Brouwer <aeb@cwi.nl>.
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  27 .TH SCALB 3 2017-09-15 "" "Linux Programmer's Manual"
  28 .SH NAME
  29 scalb, scalbf, scalbl \- multiply floating-point number
  30 by integral power of radix (OBSOLETE)
  31 .SH SYNOPSIS
  32 .B #include <math.h>
  33 .PP
  34 .BI "double scalb(double " x ", double " exp );
  35 .br
  36 .BI "float scalbf(float " x ", float " exp );
  37 .br
  38 .BI "long double scalbl(long double " x ", long double " exp );
  39 .PP
  40 Link with \fI\-lm\fP.
  41 .PP
  42 .in -4n
  43 Feature Test Macro Requirements for glibc (see
  44 .BR feature_test_macros (7)):
  45 .in
  46 .PP
  47 .ad l
  48 .BR scalb ():
  49 .RS 4
  50 _XOPEN_SOURCE\ >=\ 500
  51 .\"    || _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
  52     || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  53     || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
  54 .RE
  55 .br
  56 .BR scalbf (),
  57 .BR scalbl ():
  58 .RS 4
  59 _XOPEN_SOURCE\ >=\ 600
  60     || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  61     || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
  62 .RE
  63 .ad b
  64 .SH DESCRIPTION
  65 These functions multiply their first argument
  66 .I x
  67 by
  68 .B FLT_RADIX
  69 (probably 2)
  70 to the power of
  71 .IR exp ,
  72 that is:
  73 .PP
  74 .nf
  75     x * FLT_RADIX ** exp
  76 .fi
  77 .PP
  78 The definition of
  79 .B FLT_RADIX
  80 can be obtained by including
  81 .IR <float.h> .
  82 .\" not in /usr/include but in a gcc lib
  83 .SH RETURN VALUE
  84 On success, these functions return
  85 .IR x
  86 *
  87 .B FLT_RADIX
  88 **
  89 .IR exp .
  90 .PP
  91 If
  92 .I x
  93 or
  94 .I exp
  95 is a NaN, a NaN is returned.
  96 .PP
  97 If
  98 .I x
  99 is positive infinity (negative infinity),
 100 and
 101 .I exp
 102 is not negative infinity,
 103 positive infinity (negative infinity) is returned.
 104 .PP
 105 If
 106 .I x
 107 is +0 (\-0), and
 108 .I exp
 109 is not positive infinity, +0 (\-0) is returned.
 110 .PP
 111 If
 112 .I x
 113 is zero, and
 114 .I exp
 115 is positive infinity,
 116 a domain error occurs, and
 117 a NaN is returned.
 118 .PP
 119 If
 120 .I x
 121 is an infinity,
 122 and
 123 .I exp
 124 is negative infinity,
 125 a domain error occurs, and
 126 a NaN is returned.
 127 .PP
 128 If the result overflows,
 129 a range error occurs,
 130 and the functions return
 131 .BR HUGE_VAL ,
 132 .BR HUGE_VALF ,
 133 or
 134 .BR HUGE_VALL ,
 135 respectively, with a sign the same as
 136 .IR x .
 137 .PP
 138 If the result underflows,
 139 a range error occurs,
 140 and the functions return zero, with a sign the same as
 141 .IR x .
 142 .SH ERRORS
 143 See
 144 .BR math_error (7)
 145 for information on how to determine whether an error has occurred
 146 when calling these functions.
 147 .PP
 148 The following errors can occur:
 149 .TP
 150 Domain error: \fIx\fP is 0, and \fIexp\fP is positive infinity, \
 151 or \fIx\fP is positive infinity and \fIexp\fP is negative infinity \
 152 and the other argument is not a NaN
 153 .\" .I errno
 154 .\" is set to
 155 .\" .BR EDOM .
 156 An invalid floating-point exception
 157 .RB ( FE_INVALID )
 158 is raised.
 159 .TP
 160 Range error, overflow
 161 .\" .I errno
 162 .\" is set to
 163 .\" .BR ERANGE .
 164 An overflow floating-point exception
 165 .RB ( FE_OVERFLOW )
 166 is raised.
 167 .TP
 168 Range error, underflow
 169 .\" .I errno
 170 .\" is set to
 171 .\" .BR ERANGE .
 172 An underflow floating-point exception
 173 .RB ( FE_UNDERFLOW )
 174 is raised.
 175 .PP
 176 These functions do not set
 177 .IR errno .
 178 .\" FIXME . Is it intentional that these functions do not set errno?
 179 .\" Bug raised: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6803
 180 .\" Bug raised: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6804
 181 .SH ATTRIBUTES
 182 For an explanation of the terms used in this section, see
 183 .BR attributes (7).
 184 .TS
 185 allbox;
 186 lbw28 lb lb
 187 l l l.
 188 Interface       Attribute       Value
 189 T{
 190 .BR scalb (),
 191 .BR scalbf (),
 192 .BR scalbl ()
 193 T}      Thread safety   MT-Safe
 194 .TE
 195 .SH CONFORMING TO
 196 .BR scalb ()
 197 is specified in POSIX.1-2001, but marked obsolescent.
 198 POSIX.1-2008 removes the specification of
 199 .BR scalb (),
 200 recommending the use of
 201 .BR scalbln (3),
 202 .BR scalblnf (3),
 203 or
 204 .BR scalblnl (3)
 205 instead.
 206 The
 207 .BR scalb ()
 208 function is from 4.3BSD.
 209 .PP
 210 .BR scalbf ()
 211 and
 212 .BR scalbl ()
 213 are unstandardized;
 214 .BR scalbf ()
 215 is nevertheless present on several other systems
 216 .\" Looking at header files: scalbf() is present on the
 217 .\" BSDs, Tru64, HP-UX 11, Irix 6.5; scalbl() is on HP-UX 11 and Tru64.
 218 .SH SEE ALSO
 219 .BR ldexp (3),
 220 .BR scalbln (3)