---
name: "scalbn"
section: "3"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["linux", "freebsd"]
url: "https://new.carta.tech/scalbln"
---

# scalbn(3)

adjust exponent

Part of [scalbln(3)](/scalbln/3.md).

## NAME

**scalbln**, **scalblnf**, **scalblnl**, **scalbn**, **scalbnf**, **scalbnl** – adjust exponent

## LIBRARY

Math Library (libm, -lm)

## SYNOPSIS

**#include \<math.h\>**

*double*\

**scalbln**(*double x*, *long n*);

*float*\

**scalblnf**(*float x*, *long n*);

*long* *double*\

**scalblnl**(*long double x*, *long n*);

*double*\

**scalbn**(*double x*, *int n*);

*float*\

**scalbnf**(*float x*, *int n*);

*long* *double*\

**scalbnl**(*long double x*, *int n*);

## DESCRIPTION

These routines return *x*∗(2\*\**n*) computed by exponent manipulation.

## SEE ALSO

[ieee(3)](/ieee/3.md), [math(3)](/math/3.md)

## STANDARDS

These routines conform to ISO/IEC 9899:1999 (“ISO C99”), and they implement the Scalb function recommended by IEEE Std 754-1985.

## HISTORY

The **scalbn**() and **scalbnf**() functions appeared in 4.3BSD and FreeBSD 2.0, respectively. The **scalbln**() and **scalblnf**() functions first appeared in FreeBSD 5.3, and **scalblnl**() and **scalbln**() in FreeBSD 6.0.