ldexp(3) - BetterMan

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Options · 2

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.

NAME

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

LIBRARY

Math library (libm, -lm)

SYNOPSIS

bash

#include <math.h>

bash

double ldexp(double \nx\n, int \nexp\n);\n
\nfloat ldexpf(float \nx\n, int \nexp\n);\n
\nlong double ldexpl(long double \nx\n, int \nexp\n);

ldexpf(), ldexpl():

bash


\n
    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
\n
        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
\n
        || /* glibc <= 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 (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).

Interface	Attribute	Value
ldexp (), ldexpf (), ldexpl ()	Thread safety	MT-Safe

STANDARDS

C11, POSIX.1-2008.

HISTORY

C99, POSIX.1-2001.

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