scalbf (3)

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
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.

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

SEE ALSO

ldexp(3), scalbln(3)

Information

Source
Linux kernel
OS/version
Source updated
September 15, 2017
Page created
February 9, 2018
Page generated
December 2, 2018