1SCALBLN(3P)                POSIX Programmer's Manual               SCALBLN(3P)
2
3
4

PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
10

NAME

12       scalbln, scalblnf, scalblnl, scalbn, scalbnf, scalbnl —  compute  expo‐
13       nent using FLT_RADIX
14

SYNOPSIS

16       #include <math.h>
17
18       double scalbln(double x, long n);
19       float scalblnf(float x, long n);
20       long double scalblnl(long double x, long n);
21       double scalbn(double x, int n);
22       float scalbnf(float x, int n);
23       long double scalbnl(long double x, int n);
24

DESCRIPTION

26       The  functionality described on this reference page is aligned with the
27       ISO C standard. Any conflict between the  requirements  described  here
28       and  the  ISO C  standard is unintentional. This volume of POSIX.1‐2017
29       defers to the ISO C standard.
30
31       These functions shall compute x * FLT_RADIXn efficiently, not  normally
32       by computing FLT_RADIXn explicitly.
33
34       An  application  wishing to check for error situations should set errno
35       to zero and  call  feclearexcept(FE_ALL_EXCEPT)  before  calling  these
36       functions. On return, if errno is non-zero or fetestexcept(FE_INVALID |
37       FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero,  an  error  has
38       occurred.
39

RETURN VALUE

41       Upon    successful    completion,    these   functions   shall   return
42       x * FLT_RADIXn.
43
44       If the result would cause overflow, a range error shall occur and these
45       functions shall return ±HUGE_VAL, ±HUGE_VALF, and ±HUGE_VALL (according
46       to the sign of x) as appropriate for the return type of the function.
47
48       If the correct value would cause underflow, and is not representable, a
49       range error may occur, and scalbln(), scalblnf(), scalblnl(), scalbn(),
50       scalbnf(), and scalbnl() shall return 0.0, or (if IEC  60559  Floating-
51       Point  is  not supported) an implementation-defined value no greater in
52       magnitude  than  DBL_MIN,  FLT_MIN,  LDBL_MIN,  DBL_MIN,  FLT_MIN,  and
53       LDBL_MIN, respectively.
54
55       If x is NaN, a NaN shall be returned.
56
57       If x is ±0 or ±Inf, x shall be returned.
58
59       If n is 0, x shall be returned.
60
61       If  the  correct  value  would cause underflow, and is representable, a
62       range error may occur and the correct value shall be returned.
63

ERRORS

65       These functions shall fail if:
66
67       Range Error The result overflows.
68
69                   If the integer expression (math_errhandling  &  MATH_ERRNO)
70                   is  non-zero,  then errno shall be set to [ERANGE].  If the
71                   integer expression (math_errhandling &  MATH_ERREXCEPT)  is
72                   non-zero,  then the overflow floating-point exception shall
73                   be raised.
74
75       These functions may fail if:
76
77       Range Error The result underflows.
78
79                   If the integer expression (math_errhandling  &  MATH_ERRNO)
80                   is  non-zero,  then errno shall be set to [ERANGE].  If the
81                   integer expression (math_errhandling &  MATH_ERREXCEPT)  is
82                   non-zero, then the underflow floating-point exception shall
83                   be raised.
84
85       The following sections are informative.
86

EXAMPLES

88       None.
89

APPLICATION USAGE

91       On  error,  the  expressions  (math_errhandling   &   MATH_ERRNO)   and
92       (math_errhandling  & MATH_ERREXCEPT) are independent of each other, but
93       at least one of them must be non-zero.
94

RATIONALE

96       These functions are named so as to avoid conflicting with the  histori‐
97       cal  definition of the scalb() function from the Single UNIX Specifica‐
98       tion. The difference is that the scalb() function has a second argument
99       of  double  instead  of  int.   The scalb() function is not part of the
100       ISO C standard. The three functions whose second type is long are  pro‐
101       vided  because  the factor required to scale from the smallest positive
102       floating-point value to the largest finite  one,  on  many  implementa‐
103       tions, is too large to represent in the minimum-width int format.
104

FUTURE DIRECTIONS

106       None.
107

SEE ALSO

109       feclearexcept(), fetestexcept()
110
111       The Base Definitions volume of POSIX.1‐2017, Section 4.20, Treatment of
112       Error Conditions for Mathematical Functions, <math.h>
113
115       Portions of this text are reprinted and reproduced in  electronic  form
116       from  IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
117       table Operating System Interface (POSIX), The Open Group Base  Specifi‐
118       cations  Issue  7, 2018 Edition, Copyright (C) 2018 by the Institute of
119       Electrical and Electronics Engineers, Inc and The Open Group.   In  the
120       event of any discrepancy between this version and the original IEEE and
121       The Open Group Standard, the original IEEE and The Open Group  Standard
122       is  the  referee document. The original Standard can be obtained online
123       at http://www.opengroup.org/unix/online.html .
124
125       Any typographical or formatting errors that appear  in  this  page  are
126       most likely to have been introduced during the conversion of the source
127       files to man page format. To report such errors,  see  https://www.ker
128       nel.org/doc/man-pages/reporting_bugs.html .
129
130
131
132IEEE/The Open Group                  2017                          SCALBLN(3P)
Impressum