умножить число с плавающей запятой на целую степень системы счисления (multiply floating-point number by integral power of radix)
Имя (Name)
scalbn, scalbnf, scalbnl, scalbln, scalblnf, scalblnl - multiply
floating-point number by integral power of radix
Синопсис (Synopsis)
#include <math.h>
double scalbln(double x, long exp);
float scalblnf(float x, long exp);
long double scalblnl(long double x, long exp);
double scalbn(double x, int exp);
float scalbnf(float x, int exp);
long double scalbnl(long double x, int exp);
Link with -lm.
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
scalbln(), scalblnf(), scalblnl():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
scalbn(), scalbnf(), scalbnl():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
Описание (Description)
These functions multiply their first argument x by FLT_RADIX
(probably 2) to the power of exp, that is:
x * FLT_RADIX ** exp
The definition of FLT_RADIX can be obtained by including
<float.h>.
Возвращаемое значение (Return value)
On success, these functions return x * FLT_RADIX ** exp.
If x is a NaN, a NaN is returned.
If x is positive infinity (negative infinity), positive infinity
(negative infinity) is returned.
If x is +0 (-0), +0 (-0) is returned.
If the result overflows, a range error occurs, and the functions
return HUGE_VAL, HUGE_VALF, or HUGE_VALL, respectively, with a
sign the same as x.
If the result underflows, a range error occurs, and the functions
return zero, with a sign the same as x.
Ошибки (Error)
See math_error(7) for information on how to determine whether an
error has occurred when calling these functions.
The following errors can occur:
Range error, overflow
An overflow floating-point exception (FE_OVERFLOW) is
raised.
Range error, underflow
errno is set to ERANGE. An underflow floating-point
exception (FE_UNDERFLOW) is raised.
Версии (Versions)
These functions first appeared in glibc in version 2.1.
Атрибуты (Attributes)
For an explanation of the terms used in this section, see
attributes(7).
┌──────────────────────────────────────┬───────────────┬─────────┐
│Interface │ Attribute │ Value │
├──────────────────────────────────────┼───────────────┼─────────┤
│scalbn(), scalbnf(), scalbnl(), │ Thread safety │ MT-Safe │
│scalbln(), scalblnf(), scalblnl() │ │ │
└──────────────────────────────────────┴───────────────┴─────────┘
Стандарты (Conforming to)
C99, POSIX.1-2001, POSIX.1-2008.
Примечание (Note)
These functions differ from the obsolete functions described in
scalb(3) in the type of their second argument. The functions
described on this page have a second argument of an integral
type, while those in scalb(3) have a second argument of type
double.
If FLT_RADIX equals 2 (which is usual), then scalbn() is
equivalent to ldexp(3).
Ошибки (баги) (Bugs)
Before glibc 2.20, these functions did not set errno for range
errors.
Смотри также (See also)
ldexp(3), scalb(3)
