ldexp(3) - Linux manual page (original) (raw)

ldexp(3) Library Functions Manual ldexp(3)

NAME top

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

LIBRARY top

   Math library (_libm_, _-lm_)

SYNOPSIS top

   **#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 top

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

RETURN VALUE top

   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 top

   See [math_error(7)](../man7/math%5Ferror.7.html) for information on how to determine whether an
   error has occurred when calling these functions.

   The following errors can occur:

   Range error, overflow
          _[errno](../man3/errno.3.html)_ is set to **ERANGE**.  An overflow floating-point
          exception (**FE_OVERFLOW**) is raised.

   Range error, underflow
          _[errno](../man3/errno.3.html)_ is set to **ERANGE**.  An underflow floating-point
          exception (**FE_UNDERFLOW**) is raised.

ATTRIBUTES top

   For an explanation of the terms used in this section, see
   [attributes(7)](../man7/attributes.7.html).
   ┌──────────────────────────────────────┬───────────────┬─────────┐
   │ **Interface** │ **Attribute** │ **Value** │
   ├──────────────────────────────────────┼───────────────┼─────────┤
   │ **ldexp**(), **ldexpf**(), **ldexpl**()          │ Thread safety │ MT-Safe │
   └──────────────────────────────────────┴───────────────┴─────────┘

STANDARDS top

   C11, POSIX.1-2008.

HISTORY top

   C99, POSIX.1-2001.

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

SEE ALSO top

   [frexp(3)](../man3/frexp.3.html), [modf(3)](../man3/modf.3.html), [scalbln(3)](../man3/scalbln.3.html)

COLOPHON top

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Linux man-pages 6.10 2024-07-23 ldexp(3)

Pages that refer to this page:frexp(3), modf(3), scalb(3), scalbln(3)