Originální popis anglicky:
scalbln, scalblnf, scalblnl, scalbn, scalbnf, scalbnl - compute exponent using
FLT_RADIX
Návod, kniha: POSIX Programmer's Manual
#include <math.h>
double scalbln(double
x, long
n );
float scalblnf(float
x, long
n);
long double scalblnl(long double
x, long
n );
double scalbn(double
x, int
n);
float scalbnf(float
x, int
n);
long double scalbnl(long double
x, int
n );
These functions shall compute
x * FLT_RADIX
**n
efficiently, not normally by computing FLT_RADIX
**n explicitly.
An application wishing to check for error situations should set
errno to
zero and call
feclearexcept(FE_ALL_EXCEPT) before calling these
functions. On return, if
errno is non-zero or
fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is
non-zero, an error has occurred.
Upon successful completion, these functions shall return
x * FLT_RADIX
**n.
If the result would cause overflow, a range error shall occur and these
functions shall return ±HUGE_VAL, ±HUGE_VALF, and
±HUGE_VALL (according to the sign of
x) as appropriate for the
return type of the function.
If the correct value would cause underflow, and is not representable, a range
error may occur, and either 0.0 (if supported), or an
implementation-defined value shall be returned.
If
x is NaN, a NaN shall be returned.
If
x is ±0 or ±Inf,
x shall be returned.
If
n is 0,
x shall be returned.
If the correct value would cause underflow, and is representable, a range error
may occur and the correct value shall be returned.
These functions shall fail if:
- Range Error
- The result overflows.
If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then
errno shall be set to [ERANGE]. If the integer expression
(math_errhandling & MATH_ERREXCEPT) is non-zero, then the overflow
floating-point exception shall be raised.
These functions may fail if:
- Range Error
- The result underflows.
If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then
errno shall be set to [ERANGE]. If the integer expression
(math_errhandling & MATH_ERREXCEPT) is non-zero, then the underflow
floating-point exception shall be raised.
The following sections are informative.
None.
On error, the expressions (math_errhandling & MATH_ERRNO) and
(math_errhandling & MATH_ERREXCEPT) are independent of each other, but at
least one of them must be non-zero.
These functions are named so as to avoid conflicting with the historical
definition of the
scalb() function from the Single UNIX Specification.
The difference is that the
scalb() function has a second argument of
double instead of
int. The
scalb() function is not part
of the ISO C standard. The three functions whose second type is
long are provided because the factor required to scale from the
smallest positive floating-point value to the largest finite one, on many
implementations, is too large to represent in the minimum-width
int
format.
None.
feclearexcept() ,
fetestexcept() ,
scalb() , the Base
Definitions volume of IEEE Std 1003.1-2001, Section 4.18,
Treatment of Error Conditions for Mathematical Functions,
<math.h>
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.opengroup.org/unix/online.html
.
