# scalbln(3) — Linux manual page

SCALBLN(3)              Linux Programmer's Manual             SCALBLN(3)

## NAME         top

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

## SYNOPSIS         top

#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);

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

## DESCRIPTION         top

These functions multiply their first argument x by FLT_RADIX
(probably 2) to the power of exp, that is:

The definition of FLT_RADIX can be obtained by including
<float.h>.

## RETURN VALUE         top

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         top

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         top

These functions first appeared in glibc in version 2.1.

## ATTRIBUTES         top

For an explanation of the terms used in this section, see
attributes(7).

┌──────────────────────────────────────┬───────────────┬─────────┐
│Interface                             Attribute     Value   │
├──────────────────────────────────────┼───────────────┼─────────┤
│scalbn(), scalbnf(), scalbnl(),       │ Thread safety │ MT-Safe │
│scalbln(), scalblnf(), scalblnl()     │               │         │
└──────────────────────────────────────┴───────────────┴─────────┘

## CONFORMING TO         top

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

## NOTES         top

These functions differ from the obsolete functions described in
scalb(3) in the type of their second argument.  The functions
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         top

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