ldexpl(3)

ldexpl3

Multiply floating-point number by integral power of 2

Part of ldexp(3).

Usage

#include <math.h>

double ldexp(double x, int e); float ldexpf(float x, int e); long double ldexpl(long double x, int e);

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

Library

Math library (libm, -lm)

Overview

These functions return the result of multiplying the floating-point number x by 2 raised to the power e.

Return value

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

If e 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).

InterfaceAttributeValue
ldexp(), ldexpf(), ldexpl()Thread safetyMT-Safe

Releases

12 releases since Debian 3.1 (Sarge); the text changed 11 times.

  1. 3.1
  2. 4.0
  3. 5.0
  4. 6.0
  5. 7
  6. 8
  7. 9
  8. 10
  9. 11
  10. 12
  11. 13
  12. Arch

Standards

C11, POSIX.1-2008.

History

C99, POSIX.1-2001.

The variant returning double also conforms to SVr4, 4.3BSD, C89.

From man-pages 6.19-1 in Arch Linux 2026-11-01. Parsed by carta from the page's man source.