scalb - Man Page

multiply floating-point number by integral power of radix (OBSOLETE)

Library

Math library (libm, -lm)

Synopsis

```#include <math.h>

[[deprecated]] double scalb(double x, double exp);
[[deprecated]] float scalbf(float x, float exp);
[[deprecated]] 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

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>.

Return Value

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

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

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

InterfaceAttributeValue
scalb(), scalbf(), scalbl()Thread safetyMT-Safe

None.

History

scalb()

4.3BSD. Obsolescent in POSIX.1-2001; Removed in POSIX.1-2008, recommending the use of scalbln(3), scalblnf(3), or scalblnl(3) instead.

Bugs

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

Referenced By

The man pages scalbf(3) and scalbl(3) are aliases of scalb(3).

2023-03-30 Linux man-pages 6.04