1SCALBLN(3P)                POSIX Programmer's Manual               SCALBLN(3P)
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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.
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11

NAME

13       scalbln, scalblnf, scalblnl, scalbn, scalbnf, scalbnl —  compute  expo‐
14       nent using FLT_RADIX
15

SYNOPSIS

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

27       The  functionality described on this reference page is aligned with the
28       ISO C standard. Any conflict between the  requirements  described  here
29       and  the  ISO C  standard is unintentional. This volume of POSIX.1‐2008
30       defers to the ISO C standard.
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32       These functions shall compute x * FLT_RADIXn efficiently, not  normally
33       by computing FLT_RADIXn explicitly.
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35       An  application  wishing to check for error situations should set errno
36       to zero and  call  feclearexcept(FE_ALL_EXCEPT)  before  calling  these
37       functions. On return, if errno is non-zero or fetestexcept(FE_INVALID |
38       FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero,  an  error  has
39       occurred.
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RETURN VALUE

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

66       These functions shall fail if:
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68       Range Error The result overflows.
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70                   If the integer expression (math_errhandling  &  MATH_ERRNO)
71                   is  non-zero,  then errno shall be set to [ERANGE].  If the
72                   integer expression (math_errhandling &  MATH_ERREXCEPT)  is
73                   non-zero,  then the overflow floating-point exception shall
74                   be raised.
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76       These functions may fail if:
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78       Range Error The result underflows.
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80                   If the integer expression (math_errhandling  &  MATH_ERRNO)
81                   is  non-zero,  then errno shall be set to [ERANGE].  If the
82                   integer expression (math_errhandling &  MATH_ERREXCEPT)  is
83                   non-zero, then the underflow floating-point exception shall
84                   be raised.
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86       The following sections are informative.
87

EXAMPLES

89       None.
90

APPLICATION USAGE

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

97       These functions are named so as to avoid conflicting with the  histori‐
98       cal  definition of the scalb() function from the Single UNIX Specifica‐
99       tion. The difference is that the scalb() function has a second argument
100       of  double  instead  of  int.   The scalb() function is not part of the
101       ISO C standard. The three functions whose second type is long are  pro‐
102       vided  because  the factor required to scale from the smallest positive
103       floating-point value to the largest finite  one,  on  many  implementa‐
104       tions, is too large to represent in the minimum-width int format.
105

FUTURE DIRECTIONS

107       None.
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SEE ALSO

110       feclearexcept(), fetestexcept()
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112       The Base Definitions volume of POSIX.1‐2008, Section 4.19, Treatment of
113       Error Conditions for Mathematical Functions, <math.h>
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116       Portions of this text are reprinted and reproduced in  electronic  form
117       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
118       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
119       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
120       cal and Electronics Engineers,  Inc  and  The  Open  Group.   (This  is
121       POSIX.1-2008  with  the  2013  Technical Corrigendum 1 applied.) In the
122       event of any discrepancy between this version and the original IEEE and
123       The  Open Group Standard, the original IEEE and The Open Group Standard
124       is the referee document. The original Standard can be  obtained  online
125       at http://www.unix.org/online.html .
126
127       Any  typographical  or  formatting  errors that appear in this page are
128       most likely to have been introduced during the conversion of the source
129       files  to  man page format. To report such errors, see https://www.ker
130       nel.org/doc/man-pages/reporting_bugs.html .
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134IEEE/The Open Group                  2013                          SCALBLN(3P)
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