man3/scalbln.3

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  27 .TH SCALBLN 3 2016-03-15 "" "Linux Programmer's Manual"
  28 .SH NAME
  29 scalbn, scalbnf, scalbnl, scalbln, scalblnf, scalblnl \-
  30 multiply floating-point number by integral power of radix
  31 .SH SYNOPSIS
  32 .B #include <math.h>
  33 .sp
  34 .BI "double scalbln(double " x ", long int " exp );
  35 .br
  36 .BI "float scalblnf(float " x ", long int " exp );
  37 .br
  38 .BI "long double scalblnl(long double " x ", long int " exp );
  39 .sp
  40 .BI "double scalbn(double " x ", int " exp );
  41 .br
  42 .BI "float scalbnf(float " x ", int " exp );
  43 .br
  44 .BI "long double scalbnl(long double " x ", int " exp );
  45 .sp
  46 Link with \fI\-lm\fP.
  47 .sp
  48 .in -4n
  49 Feature Test Macro Requirements for glibc (see
  50 .BR feature_test_macros (7)):
  51 .in
  52 .sp
  53 .ad l
  54 .BR scalbln (),
  55 .BR scalblnf (),
  56 .BR scalblnl ():
  57 .RS
  58 _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
  59     || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  60 .RE
  61 .br
  62 .BR scalbn (),
  63 .BR scalbnf (),
  64 .BR scalbnl ():
  65 .RS
  66 _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
  67     || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  68     || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
  69 .RE
  70 .ad b
  71 .SH DESCRIPTION
  72 These functions multiply their first argument
  73 .I x
  74 by
  75 .B FLT_RADIX
  76 (probably 2)
  77 to the power of
  78 .IR exp ,
  79 that is:
  80 .nf
  81
  82     x * FLT_RADIX ** exp
  83 .fi
  84
  85 The definition of
  86 .B FLT_RADIX
  87 can be obtained by including
  88 .IR <float.h> .
  89 .\" not in /usr/include but in a gcc lib
  90 .SH RETURN VALUE
  91 On success, these functions return
  92 .IR x
  93 *
  94 .B FLT_RADIX
  95 **
  96 .IR exp .
  97
  98 If
  99 .I x
 100 is a NaN, a NaN is returned.
 101
 102 If
 103 .I x
 104 is positive infinity (negative infinity),
 105 positive infinity (negative infinity) is returned.
 106
 107 If
 108 .I x
 109 is +0 (\-0), +0 (\-0) is returned.
 110
 111 If the result overflows,
 112 a range error occurs,
 113 and the functions return
 114 .BR HUGE_VAL ,
 115 .BR HUGE_VALF ,
 116 or
 117 .BR HUGE_VALL ,
 118 respectively, with a sign the same as
 119 .IR x .
 120
 121 If the result underflows,
 122 a range error occurs,
 123 and the functions return zero, with a sign the same as
 124 .IR x .
 125 .SH ERRORS
 126 See
 127 .BR math_error (7)
 128 for information on how to determine whether an error has occurred
 129 when calling these functions.
 130 .PP
 131 The following errors can occur:
 132 .TP
 133 Range error, overflow
 134 .\" .I errno
 135 .\" is set to
 136 .\" .BR ERANGE .
 137 An overflow floating-point exception
 138 .RB ( FE_OVERFLOW )
 139 is raised.
 140 .TP
 141 Range error, underflow
 142 .\" .I errno
 143 .\" is set to
 144 .\" .BR ERANGE .
 145 An underflow floating-point exception
 146 .RB ( FE_UNDERFLOW )
 147 is raised.
 148 .PP
 149 These functions do not set
 150 .IR errno .
 151 .\" FIXME . Is it intentional that these functions do not set errno?
 152 .\" Bug raised: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6803
 153 .SH VERSIONS
 154 These functions first appeared in glibc in version 2.1.
 155 .SH ATTRIBUTES
 156 For an explanation of the terms used in this section, see
 157 .BR attributes (7).
 158 .TS
 159 allbox;
 160 lbw33 lb lb
 161 l l l.
 162 Interface       Attribute       Value
 163 T{
 164 .BR scalbn (),
 165 .BR scalbnf (),
 166 .BR scalbnl (),
 167 .br
 168 .BR scalbln (),
 169 .BR scalblnf (),
 170 .BR scalblnl ()
 171 T}      Thread safety   MT-Safe
 172 .TE
 173 .SH CONFORMING TO
 174 C99, POSIX.1-2001, POSIX.1-2008.
 175 .SH NOTES
 176 These functions differ from the obsolete functions described in
 177 .BR scalb (3)
 178 in the type of their second argument.
 179 The functions described on this page have a second argument
 180 of an integral type, while those in
 181 .BR scalb (3)
 182 have a second argument of type
 183 .IR double .
 184
 185 If
 186 .B FLT_RADIX
 187 equals 2 (which is usual), then
 188 .BR scalbn ()
 189 is equivalent to
 190 .BR ldexp (3).
 191 .SH SEE ALSO
 192 .BR ldexp (3),
 193 .BR scalb (3)