# scalb(3) — Linux manual page

```SCALB(3)                Linux Programmer's Manual               SCALB(3)
```

## NAME         top

```       scalb, scalbf, scalbl - multiply floating-point number by
```

## SYNOPSIS         top

```       #include <math.h>

double scalb(double x, double exp);
float scalbf(float x, float exp);
long double scalbl(long double x, long double exp);

Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):

scalb():
_XOPEN_SOURCE >= 500
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

scalbf(), scalbl():
_XOPEN_SOURCE >= 600
|| /* 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 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.
```

## 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:

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
errno is set to EDOM.  An invalid floating-point exception
(FE_INVALID) is raised.

Range error, overflow
errno is set to ERANGE.  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.
```

## ATTRIBUTES         top

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

┌──────────────────────────────────────┬───────────────┬─────────┐
│Interface                             │ Attribute     │ Value   │
├──────────────────────────────────────┼───────────────┼─────────┤
│scalb(), scalbf(), scalbl()           │ Thread safety │ MT-Safe │
└──────────────────────────────────────┴───────────────┴─────────┘
```

## CONFORMING TO         top

```       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
```

## BUGS         top

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

```       ldexp(3), scalbln(3)
```

## COLOPHON         top

```       This page is part of release 5.13 of the Linux man-pages project.
A description of the project, information about reporting bugs,