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

```
#include <math.h>
double scalbln(double x, long int exp);
float scalblnf(float x, long int exp);
long double scalblnl(long double x, long int 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
An underflow floating-point exception (

**FE_UNDERFLOW**) is raised.

These functions do not set `errno`

.

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).

This page is part of release 4.15 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/.