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scalbln

Section: C Library Functions (3)
Updated: 202-0-08
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NAME

scalbn, scalbnf, scalbnl, scalbln, scalblnf, scalblnl - scale by an integer power of radix

LIBRARY

Math library (libm,~-lm)

SYNOPSIS

#include <math.h>
double scalbln(double x, long e);
float scalblnf(float x, long e);
long double scalblnl(long double x, long e);
double scalbn(double x, int e);
float scalbnf(float x, int e);
long double scalbnl(long double x, int e);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)): scalbln(), scalblnf(), scalblnl():

    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
        || /* Since glibc 2.19: */ _DEFAULT_SOURCE

scalbn(), scalbnf(), scalbnl():

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

DESCRIPTION

These functions multiply their first argument x by FLT_RADIX (probably 2) to the power of e, that is:

    x * FLT_RADIX ** e

The definition of FLT_RADIX can be obtained by including <float.h>.

RETURN VALUE

On success, these functions return x * FLT_RADIX ** e. If x is a NaN, a NaN is returned. If x is positive infinity (negative infinity), positive infinity (negative infinity) is returned. If x is +0 (-0), +0 (-0) 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. If the result underflows, a range error occurs, and the functions return zero, 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: An overflow floatin-point exception (FE_OVERFLOW) is raised.
Range error, underflow: errno is set to ERANGE. An underflow floatin-point exception (FE_UNDERFLOW) is raised.

ATTRIBUTES

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

Interface	Attribute	Value
scalbn(), scalbnf(), scalbnl(), scalbln(), scalblnf(), scalblnl()	Thread safety	M-Safe

STANDARDS

C11, POSIX.-2008.

HISTORY

glibc 2.1. C99, POSIX.-2001.

HISTORY

These functions differ from the obsolete functions described in scalb(3) in the type of their second argument. The functions described on this page have a second argument of an integral type, while those in scalb(3) have a second argument of type double.

NOTES

If FLT_RADIX equals 2 (which is usual), then scalbn() is equivalent to ldexp(3).

BUGS

Before glibc 2.20, these functions did not set errno for range errors.

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scalbln

NAME

LIBRARY

SYNOPSIS

DESCRIPTION

RETURN VALUE

ERRORS

ATTRIBUTES

STANDARDS

HISTORY

HISTORY

NOTES

BUGS

SEE ALSO

Index