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.
10

NAME

12       scalbln, scalblnf, scalblnl, scalbn, scalbnf, scalbnl -  compute  expo‐
13       nent using FLT_RADIX
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SYNOPSIS

16       #include <math.h>
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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);
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DESCRIPTION

27       These  functions  shall  compute x * FLT_RADIX**n efficiently, not nor‐
28       mally by computing FLT_RADIX**n explicitly.
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30       An application wishing to check for error situations should  set  errno
31       to  zero  and  call  feclearexcept(FE_ALL_EXCEPT)  before calling these
32       functions.  On return, if errno is non-zero or  fetestexcept(FE_INVALID
33       |  FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has
34       occurred.
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RETURN VALUE

37       Upon   successful   completion,   these    functions    shall    return
38       x * FLT_RADIX**n.
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40       If the result would cause overflow, a range error shall occur and these
41       functions shall return ±HUGE_VAL, ±HUGE_VALF, and ±HUGE_VALL (according
42       to the sign of x) as appropriate for the return type of the function.
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44       If the correct value would cause underflow, and is not representable, a
45       range error may occur, and  either 0.0 (if supported), or an  implemen‐
46       tation-defined value shall be returned.
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48       If x is NaN, a NaN shall be returned.
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50       If x is ±0 or ±Inf, x shall be returned.
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52       If n is 0, x shall be returned.
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54       If  the  correct  value  would cause underflow, and is representable, a
55       range error may occur and the correct value shall be returned.
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ERRORS

58       These functions shall fail if:
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60       Range Error
61              The result overflows.
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63       If the integer expression (math_errhandling & MATH_ERRNO) is  non-zero,
64       then  errno  shall  be  set  to  [ERANGE].  If  the  integer expression
65       (math_errhandling & MATH_ERREXCEPT)  is  non-zero,  then  the  overflow
66       floating-point exception shall be raised.
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69       These functions may fail if:
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71       Range Error
72              The result underflows.
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74       If  the integer expression (math_errhandling & MATH_ERRNO) is non-zero,
75       then errno  shall  be  set  to  [ERANGE].  If  the  integer  expression
76       (math_errhandling  &  MATH_ERREXCEPT)  is  non-zero, then the underflow
77       floating-point exception shall be raised.
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80       The following sections are informative.
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EXAMPLES

83       None.
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APPLICATION USAGE

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

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

101       None.
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SEE ALSO

104       feclearexcept(),  fetestexcept(),  scalb(), the Base Definitions volume
105       of IEEE Std 1003.1-2001, Section 4.18, Treatment  of  Error  Conditions
106       for Mathematical Functions, <math.h>
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109       Portions  of  this text are reprinted and reproduced in electronic form
110       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
111       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
112       Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of
113       Electrical  and  Electronics  Engineers, Inc and The Open Group. In the
114       event of any discrepancy between this version and the original IEEE and
115       The  Open Group Standard, the original IEEE and The Open Group Standard
116       is the referee document. The original Standard can be  obtained  online
117       at http://www.opengroup.org/unix/online.html .
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121IEEE/The Open Group                  2003                          SCALBLN(3P)
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