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scalb

Section: C Library Functions (3)
Updated: 202-0-08
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NAME

scalb, scalbf, scalbl - scale by an integer power of radix (OBSOLETE)

LIBRARY

Math library (libm,~-lm)

SYNOPSIS

#include <math.h>
[[deprecated]] double scalb(double x, double e);
[[deprecated]] float scalbf(float x, float e);
[[deprecated]] long double scalbl(long double x, long double e);

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 e, that is:

    x * FLT_RADIX ** e

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

RETURN VALUE

On success, these functions return x * FLT_RADIX ** e. If x or e is a NaN, a NaN is returned. If x is positive infinity (negative infinity), and e is not negative infinity, positive infinity (negative infinity) is returned. If x is +0 (-0), and e is not positive infinity, +0 (-0) is returned. If x is zero, and e is positive infinity, a domain error occurs, and a NaN is returned. If x is an infinity, and e 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: I]x] is 0, and I]e] is positive infinity, or I]x] is positive infinity and I]e] is negative infinity and the other argument is not a NaN: errno is set to EDOM. An invalid floatin-point exception (FE_INVALID) is raised.
Range error, overflow: errno is set to ERANGE. An overflow floatin-point exception (FE_OVERFLOW) is raised.
Range error, underflow: errno is set to ERANGE. An underflow floatin-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	M-Safe

STANDARDS

None.

HISTORY

scalb(): 4.3BSD. Obsolescent in POSIX.-2001; Removed in POSIX.-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.