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

```
#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)):

```
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
```

These functions return the result of multiplying the floating-point number `x`

by 2 raised to the power `exp`

.

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`

.

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.

For an explanation of the terms used in this section, see attributes(7).

Interface | Attribute | Value |

ldexp(), ldexpf(), ldexpl() | Thread safety | MT-Safe |

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

The variant returning `double`

also conforms to SVr4, 4.3BSD, C89.

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project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.