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 ** exp`

The 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:

- 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.

These functions first appeared in glibc in version 2.1.

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.

This page is part of release 5.10 of the Linux `man-pages`

project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.