SCALB(3) Linux Programmer's Manual SCALB(3)
scalb, scalbf, scalbl - multiply floating-point number by integral power of radix (OBSO-
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)):
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 ||
_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600
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>.
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
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.
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.
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
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