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man:ldexpf

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 (nega-
tive 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).```
```     allbox; lbw27 lb lb  l  l  l.   Interface Attribute Value  T{  ldexp(),
ldexpf(), ldexpl() T}   Thread safety  MT-Safe```

CONFORMING TO

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

`     frexp(3), modf(3), scalbln(3)`
```     This  page  is  part of release 4.16 of the Linux man-pages project.  A
`                                2017-09-15                          LDEXP(3)` 