scalb, scalbf, scalbl - multiply floating-point number by integral power of radix (OBSOLETE)
#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)):
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 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
.
See math_error(7) for information on how to determine whether an error has occurred when calling these functions.
The following errors can occur:
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 NaNerrno
is set to EDOM. An invalid
floating-point exception (FE_INVALID) is raised.
errno
is set to ERANGE. An overflow
floating-point exception (FE_OVERFLOW) is raised.
errno
is set to ERANGE. An underflow
floating-point exception (FE_UNDERFLOW) is raised.
For an explanation of the terms used in this section, see attributes(7).
Interface | Attribute | Value |
scalb(), scalbf(), scalbl() | Thread safety | MT-Safe |
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
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/.