scalb(3) — Linux manual pages

Linux manual pages	Section 3: Subroutines

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)`;

Note

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
`scalb`():
`_BSD_SOURCE` \|\| `_SVID_SOURCE` \|\| `_XOPEN_SOURCE` >= 500 \|\| `_XOPEN_SOURCE` && `_XOPEN_SOURCE_EXTENDED`
`scalbf`(), `scalbl`():
`_BSD_SOURCE` \|\| `_SVID_SOURCE` \|\| `_XOPEN_SOURCE` >= 600

	Note
	Link with `−lm`.

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: 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.

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

COLOPHON

This page is part of release 3.52 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man−pages/.

  Copyright 2004 Andries Brouwer <aebcwi.nl>.
and Copyright 2008, Linux Foundation, written by Michael Kerrisk
    <mtk.manpagesgmail.com>

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