ldexp, ldexpf, ldexpl - multiply floating-point number by integral power of 2
Math library (libm
, -lm
)
#include <math.h>
double ldexp(double x, int exp);
float ldexpf(float x, int exp);
long double ldexpl(long double x, int exp);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
These functions return the result of multiplying the floating-point
number x
by 2 raised to the power exp
.
On success, these functions return x * (2^exp)
.
If exp
is zero, then x
is returned.
If x
is a NaN, a NaN is returned.
If x
is positive infinity (negative infinity), positive
infinity (negative infinity) is returned.
If the result underflows, a range error occurs, and zero 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
.
See math_error(7) for information on how to determine whether an error has occurred when calling these functions.
The following errors can occur:
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 |
C11, POSIX.1-2008.
C99, POSIX.1-2001.
The variant returning double
also conforms to SVr4, 4.3BSD,
C89.