Manpage of LDEXP

LDEXP

Section: Linux Programmer's Manual (3)
Updated: 2016-03-15
Index
 

NAME

ldexp, ldexpf, ldexpl - multiply floating-point number by integral power of 2  

SYNOPSIS

#include <math.h>double ldexp(double x, int exp);
float ldexpf(float x, int exp);
long double ldexpl(long double x, int exp);

Link with -lm.

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 versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
 

DESCRIPTION

These functions return the result of multiplying the floating-point number xby 2 raised to the power exp.  

RETURN VALUE

On success, these functions return x * (2^exp).

If expis zero, then xis returned.

If xis a NaN, a NaN is returned.

If xis 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.  

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
errnois set to ERANGE. An overflow floating-point exception (FE_OVERFLOW) is raised.
Range error, underflow
errnois set to ERANGE. An underflow floating-point exception (FE_UNDERFLOW) is raised.
 

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).
InterfaceAttributeValue
ldexp(), ldexpf(), ldexpl() Thread safetyMT-Safe
 

CONFORMING TO

C99, POSIX.1-2001, POSIX.1-2008.

The variant returning doublealso conforms to SVr4, 4.3BSD, C89.  

SEE ALSO

frexp(3), modf(3), scalbln(3)


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
ATTRIBUTES
CONFORMING TO
SEE ALSO

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