ldexp(3) Library Functions Manual ldexp(3)
NAME
ldexp, ldexpf, ldexpl - multiply floating-point number by integral
power of 2
LIBRARY
Math library (libm, -lm)
SYNOPSIS
#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)):
ldexpf(), ldexpl():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
DESCRIPTION
These functions return the result of multiplying the floating-point
number x by 2 raised to the power exp.
RETURN VALUE
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 (nega-
tive 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.
ERRORS
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.
ATTRIBUTES
For an explanation of the terms used in this section, see at-
tributes(7).
┌────────────────────────────────────────────┬───────────────┬─────────┐
│Interface │ Attribute │ Value │
├────────────────────────────────────────────┼───────────────┼─────────┤
│ldexp(), ldexpf(), ldexpl() │ Thread safety │ MT-Safe │
└────────────────────────────────────────────┴───────────────┴─────────┘
STANDARDS
C99, POSIX.1-2001, POSIX.1-2008.
The variant returning double also conforms to SVr4, 4.3BSD.
SEE ALSO
frexp(3), modf(3), scalbln(3)
Linux man-pages 6.03 2023-02-10 ldexp(3)
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