1SCALBLN(P)                 POSIX Programmer's Manual                SCALBLN(P)
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NAME

6       scalbln,  scalblnf,  scalblnl, scalbn, scalbnf, scalbnl - compute expo‐
7       nent using FLT_RADIX
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SYNOPSIS

10       #include <math.h>
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12       double scalbln(double x, long n);
13       float scalblnf(float x, long n);
14       long double scalblnl(long double x, long n);
15       double scalbn(double x, int n);
16       float scalbnf(float x, int n);
17       long double scalbnl(long double x, int n);
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DESCRIPTION

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

31       Upon    successful    completion,    these   functions   shall   return
32       x * FLT_RADIX**n.
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34       If the result would cause overflow, a range error shall occur and these
35       functions shall return ±HUGE_VAL, ±HUGE_VALF, and ±HUGE_VALL (according
36       to the sign of x) as appropriate for the return type of the function.
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38       If the correct value would cause underflow, and is not representable, a
39       range error may occur, and    either 0.0 (if supported), or   an imple‐
40       mentation-defined value shall be returned.
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42       If x is NaN, a NaN shall be returned.
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44       If x is ±0 or ±Inf, x shall be returned.
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46       If n is 0, x shall be returned.
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48       If the correct value would cause underflow,  and  is  representable,  a
49       range error may occur and the correct value shall be returned.
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ERRORS

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

77       None.
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APPLICATION USAGE

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

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

95       None.
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SEE ALSO

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