## Name

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

## 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`)`;

Note
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`
Note Link with `−lm`.

## 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.

## VERSIONS

These functions first appeared in glibc in version 2.1.

## 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

## CONFORMING TO

C99, POSIX.1-2001, POSIX.1-2008.

## NOTES

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).

## BUGS

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

This page is part of release 5.11 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/.