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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():

_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
or cc -std=c99

Description

The ldexp() function returns 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

Multithreading (see pthreads(7) )

The ldexp(), ldexpf(), and ldexpl() functions are thread-safe.

Conforming to

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

See Also

frexp(3) , modf(3) , scalbln(3)

Colophon

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