scalb, scalbf, scalbl - multiply floating-point number by integral power of radix (OBSOLETE)
Math library (libm
, -lm
)
#include <math.h>
[[deprecated]] double scalb(double x, double exp);
[[deprecated]] float scalbf(float x, float exp);
[[deprecated]] long double scalbl(long double x, long double exp);
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 |
Thread safety | MT-Safe |
None.
Before glibc 2.20, these functions did not set errno
for
domain and range errors.