# NAME

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

# SYNOPSIS

#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

# 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).

 Interface Attribute Value scalb(), scalbf(), scalbl() Thread safety MT-Safe

# CONFORMING TO

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

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

This page is part of release 5.10 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/.