scalb, scalbf, scalbl - multiply floating-point number by integral power of
radix (OBSOLETE)

**#include <math.h>**
**double scalb(double ***x***, double ***exp***);**

**float scalbf(float ***x***, float ***exp***);**

**long double scalbl(long double ***x***, long double
***exp***);**
Link with

*-lm*.

Feature Test Macro Requirements for glibc (see

**feature_test_macros**(7)):

**scalb**():

_XOPEN_SOURCE >= 500

|| /* Since glibc 2.19: */ _DEFAULT_SOURCE

|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

**scalbf**(),

**scalbl**():

_XOPEN_SOURCE >= 600

|| /* 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* or

*exp* is a NaN, a NaN is returned.

If

*x* is positive infinity (negative infinity), and

*exp* is not
negative infinity, positive infinity (negative infinity) is returned.

If

*x* is +0 (-0), and

*exp* is not positive infinity, +0 (-0) is
returned.

If

*x* is zero, and

*exp* is positive infinity, a domain error occurs,
and a NaN is returned.

If

*x* is an infinity, and

*exp* is negative infinity, a domain error
occurs, and a NaN 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:

- Domain error:
*x* is 0, and *exp* is positive infinity, or
*x* is positive infinity and *exp* is negative infinity and the
other argument is not a NaN
- An invalid floating-point exception (
**FE_INVALID**) is raised.

- 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*.

For an explanation of the terms used in this section, see

**attributes**(7).

Interface |
Attribute |
Value |

scalb (), scalbf (), scalbl () |
Thread safety |
MT-Safe |

**scalb**() is specified in POSIX.1-2001, but marked obsolescent.
POSIX.1-2008 removes the specification of

**scalb**(), recommending the use
of

**scalbln**(3),

**scalblnf**(3), or

**scalblnl**(3) instead. The

**scalb**() function is from 4.3BSD.

**scalbf**() and

**scalbl**() are unstandardized;

**scalbf**() is
nevertheless present on several other systems

**ldexp**(3),

**scalbln**(3)