scalbn, scalbnf, scalbnl, scalbln, scalblnf, scalblnl - multiply floating-point number by integral power of radix
#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 versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
These functions multiply their first argument x by FLT_RADIX (probably 2) to the power of exp, that is:
x * FLT_RADIX ** expThe definition of FLT_RADIX can be obtained by including <float.h>.
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.
See math_error(7) for information on how to determine whether an error has occurred when calling these functions.
The following errors can occur:
An overflow floating-point exception (FE_OVERFLOW) is raised.
errno is set to ERANGE. An underflow floating-point exception (FE_UNDERFLOW) is raised.
These functions first appeared in glibc in version 2.1.
For an explanation of the terms used in this section, see attributes(7).
| Interface | Attribute | Value |
| scalbn(), scalbnf(), scalbnl(), scalbln(), scalblnf(), scalblnl() |
Thread safety | MT-Safe |
C99, POSIX.1-2001, POSIX.1-2008.
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).
Before glibc 2.20, these functions did not set errno for range errors.
ldexp(3), scalb(3)
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