1scalb(3)                   Library Functions Manual                   scalb(3)
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3
4

NAME

6       scalb,  scalbf,  scalbl  -  multiply  floating-point number by integral
7       power of radix (OBSOLETE)
8

LIBRARY

10       Math library (libm, -lm)
11

SYNOPSIS

13       #include <math.h>
14
15       [[deprecated]] double scalb(double x, double exp);
16       [[deprecated]] float scalbf(float x, float exp);
17       [[deprecated]] long double scalbl(long double x, long double exp);
18
19   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
20
21       scalb():
22           _XOPEN_SOURCE >= 500
23               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
24               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
25
26       scalbf(), scalbl():
27           _XOPEN_SOURCE >= 600
28               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
29               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
30

DESCRIPTION

32       These functions multiply their first argument x by FLT_RADIX  (probably
33       2) to the power of exp, that is:
34
35           x * FLT_RADIX ** exp
36
37       The definition of FLT_RADIX can be obtained by including <float.h>.
38

RETURN VALUE

40       On success, these functions return x * FLT_RADIX ** exp.
41
42       If x or exp is a NaN, a NaN is returned.
43
44       If  x is positive infinity (negative infinity), and exp is not negative
45       infinity, positive infinity (negative infinity) is returned.
46
47       If x is +0 (-0), and exp is not positive infinity, +0 (-0) is returned.
48
49       If x is zero, and exp is positive infinity, a domain error occurs,  and
50       a NaN is returned.
51
52       If  x  is an infinity, and exp is negative infinity, a domain error oc‐
53       curs, and a NaN is returned.
54
55       If the result overflows, a range error occurs, and the functions return
56       HUGE_VAL,  HUGE_VALF,  or HUGE_VALL, respectively, with a sign the same
57       as x.
58
59       If the result underflows, a range error occurs, and the  functions  re‐
60       turn zero, with a sign the same as x.
61

ERRORS

63       See  math_error(7) for information on how to determine whether an error
64       has occurred when calling these functions.
65
66       The following errors can occur:
67
68       Domain error: x is 0, and exp is positive infinity, or  x  is  positive
69       infinity  and  exp is negative infinity and the other argument is not a
70       NaN
71              errno is set  to  EDOM.   An  invalid  floating-point  exception
72              (FE_INVALID) is raised.
73
74       Range error, overflow
75              errno  is  set  to ERANGE.  An overflow floating-point exception
76              (FE_OVERFLOW) is raised.
77
78       Range error, underflow
79              errno is set to ERANGE.  An underflow  floating-point  exception
80              (FE_UNDERFLOW) is raised.
81

ATTRIBUTES

83       For  an  explanation  of  the  terms  used  in  this  section,  see at‐
84       tributes(7).
85
86       ┌────────────────────────────────────────────┬───────────────┬─────────┐
87Interface                                   Attribute     Value   
88       ├────────────────────────────────────────────┼───────────────┼─────────┤
89scalb(), scalbf(), scalbl()                 │ Thread safety │ MT-Safe │
90       └────────────────────────────────────────────┴───────────────┴─────────┘
91

STANDARDS

93       None.
94

HISTORY

96       scalb()
97              4.3BSD.  Obsolescent in POSIX.1-2001; Removed  in  POSIX.1-2008,
98              recommending  the use of scalbln(3), scalblnf(3), or scalblnl(3)
99              instead.
100

BUGS

102       Before glibc 2.20, these functions did not set  errno  for  domain  and
103       range errors.
104

SEE ALSO

106       ldexp(3), scalbln(3)
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108
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110Linux man-pages 6.05              2023-07-20                          scalb(3)
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