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():

DESCRIPTION¶

The ldexp() function returns 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 (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

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¶

Multithreading (see pthreads(7))¶

The ldexp(), ldexpf(), and ldexpl() functions are thread-safe.

CONFORMING TO¶

C99, POSIX.1-2001. The variant returning double also conforms to SVr4, 4.3BSD, C89.

SEE ALSO¶

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

COLOPHON¶

This page is part of release 3.74 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at http://www.kernel.org/doc/man-pages/.