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);
ldexpf(),
ldexpl():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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:
- Range error, overflow
-
errno is set to ERANGE. An overflow
floating-point exception (FE_OVERFLOW) is raised.
- Range error, underflow
-
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 |
ldexp (), ldexpf (), ldexpl () |
Thread safety |
MT-Safe |
C99, POSIX.1-2001, POSIX.1-2008.
The variant returning
double also conforms to SVr4, 4.3BSD.
frexp(3),
modf(3),
scalbln(3)