# NAME

scalbn, scalbnf, scalbnl, scalbln, scalblnf, scalblnl - multiply floating-point number by integral power of radix

# LIBRARY

Math library (`libm`, `-lm`)

# 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);``````

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``````

# 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>`.

# 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`.

# ERRORS

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.

# ATTRIBUTES

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

# STANDARDS

C11, POSIX.1-2008.

# HISTORY

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`.

# NOTES

If FLT_RADIX equals 2 (which is usual), then scalbn() is equivalent to ldexp(3).

# BUGS

Before glibc 2.20, these functions did not set `errno` for range errors.