SIMPLE SOLUTIONS

# LDEXP(3) - Linux man page online | Library functions

Multiply floating-point number by integral power of 2.

Chapter
2017-09-15
LDEXP(3) Linux Programmer's Manual LDEXP(3)

## 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 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

For an explanation of the terms used in this section, see attributes(7). ┌────────────────────────────┬───────────────┬─────────┐ │Interface │ Attribute │ Value │ ├────────────────────────────┼───────────────┼─────────┤ │ldexp(), ldexpf(), ldexpl() │ Thread safety │ MT-Safe │ └────────────────────────────┴───────────────┴─────────┘

## CONFORMING TO

C99, POSIX.1-2001, POSIX.1-2008. The variant returning double also conforms to SVr4, 4.3BSD, C89.